diff --git a/content/glossary/a-c.md b/content/glossary/a-c.md new file mode 100644 index 0000000..58c3b13 --- /dev/null +++ b/content/glossary/a-c.md @@ -0,0 +1,917 @@ +--- +title: Glossary, A to C +--- + +# A to C + +## A + +### A-law +A companding algorithm that squeezes the dynamic range of speech before it is coded as 8-bit PCM. It is one of the two variants of ITU-T G.711, used in Europe and most of the world outside North America and Japan. + +See also: [Mu-law](l-n.md#mu-law), [G.711](g-k.md#g711), [PCM](o-r.md#pcm). + +### AA +**Authoritative Answer.** A flag in a DNS response that says the server answering owns the zone for the name asked about, rather than passing on a cached answer. + +See also: [DNS](d-f.md#dns), [Authoritative Answer](#authoritative-answer). + +### AAC +**Advanced Audio Coding.** A lossy audio coding format, standardised in MPEG-2 and MPEG-4 as the successor to MP3. At the same bit rate it usually sounds better than MP3. HE-AAC (AAC+) is a variant tuned for low bit rates, used in digital radio such as DAB+. + +See also: [MP3](l-n.md#mp3), [MPEG](l-n.md#mpeg), [Audio Codecs](#audio-codecs). + +### AAL1 +**ATM Adaptation Layer 1.** The ATM adaptation layer for constant bit rate, connection-oriented traffic with tight timing, such as uncompressed voice and circuit emulation. It does not retransmit lost cells; it reports them and leaves recovery to the application. + +See also: [ATM](#atm), [AAL2](#aal2), [AAL5](#aal5). + +### AAL2 +**ATM Adaptation Layer 2.** The ATM adaptation layer for low-delay, variable bit rate traffic, mainly compressed voice. It packs short packets from several users into one ATM connection, and was used on the Iu interfaces of UMTS. It is defined in ITU-T I.363.2. + +See also: [ATM](#atm), [ALCAP](#alcap), [UMTS](s-z.md#umts). + +### AAL5 +**ATM Adaptation Layer 5.** The ATM adaptation layer for variable-length data packets of up to 65,535 octets, and the one most used for carrying IP over ATM. It puts its control information in an 8-octet trailer, including a 32-bit CRC, rather than a header. + +See also: [ATM](#atm), [CRC](#crc). + +### Acceptance Test +A formal test, agreed with the customer, whose result decides whether a release is accepted. + +See also: [Acceptance Testing](#acceptance-testing), [ATDD](#atdd). + +### Acceptance Testing +Testing that checks a system against the behaviour its customer or users expect, usually written as concrete examples or scenarios. The aim is often to automate those examples so they run with every build. + +See also: [Acceptance Test](#acceptance-test), [ATDD](#atdd), [BDD](#bdd). + +### Activity +A piece of work in a project that uses time and resources. Activities and tasks are near synonyms. PMBOK treats tasks as what an activity breaks down into. + +See also: [Task](s-z.md#task), [Work Breakdown Structure](s-z.md#work-breakdown-structure). + +### Activity Model +A model, such as a UML activity diagram, that shows the steps of a process or workflow and the flow of control between them. + +See also: [UML](s-z.md#uml), [Model](l-n.md#model). + +### AD +**Active Directory.** Microsoft's directory service for Windows domain networks. Domain controllers running Active Directory Domain Services authenticate users and computers, and apply security policy across the domain. + +See also: [LDAP](l-n.md#ldap), [Kerberos](g-k.md#kerberos). + +### Ad Hoc Testing +See [Informal Testing](g-k.md#informal-testing). + +### Ada +A strongly and statically typed programming language, descended from Pascal, with built-in support for concurrency, contracts and protected objects. It is used where safety matters, such as avionics and rail. The language is standardised as ISO/IEC 8652. + +See also: [Pascal](o-r.md#pascal). + +### ADR +**Architecture Decision Record.** A short document that records one significant architecture decision: its context, the options considered, the choice made and its consequences. ADRs are kept with the code and are not edited once accepted; a later ADR supersedes an earlier one. + +### ADSL +**Asymmetric Digital Subscriber Line.** A form of DSL that carries broadband over an ordinary copper telephone line, with more bandwidth downstream to the customer than upstream. + +See also: [DSL](d-f.md#dsl), [SDSL](s-z.md#sdsl), [VDSL](s-z.md#vdsl), [DSLAM](d-f.md#dslam). + +### AES +**Advanced Encryption Standard.** A symmetric block cipher, chosen by NIST in 2001 from the Rijndael family. It has a 128-bit block and keys of 128, 192 or 256 bits, and replaced DES as the default cipher for bulk encryption. + +See also: [DES](d-f.md#des), [Triple DES](s-z.md#triple-des), [NIST](l-n.md#nist). + +### Agent +In a project charter, another name for the [Project Sponsor](o-r.md#project-sponsor). + +### Agile +An approach to projects that delivers requirements in small increments, with frequent feedback, rather than in one pass at the end. + +See also: [Agile development](#agile-development), [Agile Manifesto](#agile-manifesto), [Scrum](s-z.md#scrum). + +### Agile development +An umbrella term for iterative, incremental ways of developing software, such as Scrum, XP, Lean and DSDM. + +See also: [Agile](#agile), [Scrum](s-z.md#scrum), [XP](s-z.md#xp), [DSDM](d-f.md#dsdm). + +### Agile Manifesto +The 2001 statement of the values behind agile development. It prefers individuals and interactions to processes and tools, and working software to comprehensive documentation. It also prefers customer collaboration to contract negotiation, and responding to change to following a plan. + +See also: [Agile](#agile). + +### AIS +**Alarm Indication Signal.** A signal, all ones, that a transmission element sends downstream in place of traffic when the link feeding it has failed. It keeps the framing intact and tells equipment further along that the fault is upstream. + +See also: [SDH](s-z.md#sdh), [PDH](o-r.md#pdh). + +### ALCAP +**Access Link Control Application Part.** The UMTS control protocol that sets up and releases AAL2 connections in the radio access network, multiplexing many users onto one AAL2 path. It is the 3GPP version of ITU-T Q.2630.2. + +See also: [AAL2](#aal2), [UTRAN](s-z.md#utran). + +### Amazon EC2 +**Amazon Elastic Compute Cloud.** The AWS service that rents virtual machines, called instances, started from machine images and paid for by the second while they run. + +See also: [AWS](#aws), [IaaS](g-k.md#iaas). + +### AMP +**Asymmetric Multiprocessing.** A multiprocessor design in which the processors have different roles, for example one running the operating system and the others running dedicated tasks. It is common in embedded systems that pair a general-purpose core with a real-time one. + +See also: [SMP](s-z.md#smp), [RTOS](o-r.md#rtos). + +### AMR-NB +**Adaptive Multi-Rate Narrowband.** The 3GPP speech codec for narrowband (300 to 3,400 Hz) speech, at eight bit rates from 4.75 to 12.2 kbit/s. The network picks the rate to suit the radio conditions. It is the standard codec for GSM and UMTS voice. + +See also: [AMR-WB](#amr-wb), [GSM AMR](g-k.md#gsm-amr), [Audio Codecs](#audio-codecs). + +### AMR-WB +**Adaptive Multi-Rate Wideband.** The wideband (50 to 7,000 Hz) version of AMR, also standardised as ITU-T G.722.2. It gives the "HD voice" quality used in VoLTE. + +See also: [AMR-NB](#amr-nb), [VoLTE](s-z.md#volte), [G.722](g-k.md#g722). + +### Analogy Estimation +Estimating new work by comparing it with similar work done before, and adjusting for the differences. + +See also: [Estimation](d-f.md#estimation), [Expert Judgement](d-f.md#expert-judgement). + +### Android +Google's mobile operating system, built on the Linux kernel and used on most smartphones and tablets, as well as TVs, cars and watches. + +See also: [Linux](l-n.md#linux). + +### ANDSF +**Access Network Discovery and Selection Function.** A 3GPP function that tells a mobile device which non-3GPP access networks, such as Wi-Fi, are nearby. It also gives the device policies for choosing between them and the mobile network. + +See also: [E-UTRAN](d-f.md#e-utran), [Wi-Fi](s-z.md#wi-fi). + +### ANSI +**American National Standards Institute.** The private, non-profit body that coordinates voluntary standards in the United States and represents the country at ISO. + +See also: [ISO](g-k.md#iso). + +### Antipattern +A common response to a recurring problem that looks reasonable but usually makes things worse. + +See also: [Pattern](o-r.md#pattern), [Design Pattern](d-f.md#design-pattern). + +### Anycast +An addressing and routing method in which one address is announced from several places, and the network delivers each packet to the nearest one by its routing metrics. DNS root servers and content delivery networks use it. + +See also: [Unicast](s-z.md#unicast), [Multicast](l-n.md#multicast), [Broadcast](#broadcast), [Geocast](g-k.md#geocast). + +### AOP +**Aspect-Oriented Programming.** A programming paradigm that separates cross-cutting concerns, such as logging or security checks, from the main logic. Code called advice is added at points chosen by a pattern called a pointcut, without editing the code it applies to. + +See also: [Programming paradigm](o-r.md#programming-paradigm), [OO](o-r.md#oo). + +### API +**Application Programming Interface.** A defined set of calls, messages or endpoints through which one piece of software uses another. + +See also: [REST](o-r.md#rest), [SDK](s-z.md#sdk). + +### APN +**Access Point Name.** The name a mobile device gives when it opens a data connection. It tells the operator which packet data network to connect it to, such as the public internet or a private company network, and so which addresses and policies apply. + +See also: [GGSN](g-k.md#ggsn), [PGW](o-r.md#pgw), [GPRS](g-k.md#gprs). + +### Architecture +The top-level structure of a system: its main parts, how they relate, and the principles behind its design. + +See also: [ADR](#adr), [High Level Design](g-k.md#high-level-design), [TOGAF](s-z.md#togaf). + +### ARP spoofing +An attack on a local network in which the attacker sends forged ARP replies. Other hosts then link the attacker's MAC address to someone else's IP address, often the default gateway's. Traffic then flows through the attacker, who can read, change or drop it. It is also called ARP cache poisoning. + +See also: [RARP](o-r.md#rarp), [MAC Spoofing](l-n.md#mac-spoofing), [DNS Spoofing](d-f.md#dns-spoofing). + +### Artefact +A tangible product of work, such as a document, a model, source code or a built system. + +See also: [Deliverable](d-f.md#deliverable), [Work Product](s-z.md#work-product). + +### ASCII +**American Standard Code for Information Interchange.** A 7-bit character encoding for English text, control codes and common symbols. UTF-8 and most other modern encodings keep ASCII as their first 128 characters. + +See also: [Unicode](s-z.md#unicode), [UTF-8](s-z.md#utf-8). + +### ASN.1 {#asn1} +**Abstract Syntax Notation One.** A language for describing data structures independently of how they are encoded, together with standard encoding rules such as BER, DER and PER. It is widely used in telecoms protocols and in cryptography, for example in X.509 certificates. + +See also: [BER](#ber), [DER](d-f.md#der), [PER](o-r.md#per), [CER](#cer), [X.509](s-z.md#x509). + +### Assessment +A review of a project's or an organisation's state or practices, often by someone independent. + +See also: [Audit](#audit), [Review](o-r.md#review). + +### ATDD +**Acceptance Test-Driven Development.** A practice in which customer, developer and tester agree acceptance tests before the feature is built, and the tests then drive the work. + +See also: [TDD](s-z.md#tdd), [BDD](#bdd), [Three Amigos](s-z.md#three-amigos). + +### ATM +**Asynchronous Transfer Mode.** A connection-oriented switching technology that carries voice, video and data in fixed 53-byte cells. It was the basis of broadband ISDN and was widely used in carrier backbones and DSL access networks before IP and Ethernet replaced it. + +See also: [AAL1](#aal1), [AAL2](#aal2), [AAL5](#aal5), [VPI](s-z.md#vpi), [VCI](s-z.md#vci). + +### Audio Codecs +Software or hardware that encodes and decodes digital audio in a given coding format, usually compressing it. Speech codecs such as G.711, AMR and Opus are tuned for voice calls; music codecs such as MP3, AAC and Vorbis for general audio. + +See also: [Codecs](#codecs), [G.711](g-k.md#g711), [OPUS](o-r.md#opus), [AAC](#aac). + +### Audit +A formal, independent assessment, usually against a standard or a contract. + +See also: [Assessment](#assessment). + +### Author +In a review, the person who wrote the artefact under review and who represents its viewpoint. + +See also: [Review](o-r.md#review), [Inspection](g-k.md#inspection). + +### Authoritative Answer +A DNS response from a server that is an authority for the zone holding the name asked about. The AA flag in the response header marks it. + +See also: [AA](#aa), [DNS](d-f.md#dns). + +### Authority +In a project charter, the person who funds and champions the project: the [Project Sponsor](o-r.md#project-sponsor). + +### Automated Build +A build that runs from start to finish without anyone stepping in, using only what is in version control, so that anyone can repeat it at any time. + +See also: [Build](#build), [Continuous Integration](#continuous-integration). + +### Automated Testing +Running tests and checking their results with tools rather than by hand. + +See also: [Manual Testing](l-n.md#manual-testing), [Regression testing](o-r.md#regression-testing). + +### Awk +A small language for processing text line by line, found on every Unix-like system. An Awk script is a list of patterns and actions, and it is often used for one-line reports and data extraction in pipelines. + +See also: [Sed](s-z.md#sed), [Shell Scripting](s-z.md#shell-scripting). + +### AWS +**Amazon Web Services.** Amazon's cloud computing platform: virtual machines, storage, databases, networking and many managed services, rented on demand. + +See also: [Amazon EC2](#amazon-ec2), [Azure](#azure), [Google Cloud Platform](g-k.md#google-cloud-platform). + +### Azure +Microsoft's cloud computing platform, offering infrastructure, platform and software as a service. + +See also: [AWS](#aws), [Google Cloud Platform](g-k.md#google-cloud-platform), [IaaS](g-k.md#iaas), [PaaS](o-r.md#paas). + +## B + +### B2B +**Business-to-business.** Trade between businesses, such as a manufacturer buying parts or a retailer buying stock, as opposed to selling to consumers. + +See also: [B2C](#b2c). + +### B2C +**Business-to-consumer.** Selling goods or services directly to the people who use them. + +See also: [B2B](#b2b). + +### Backhaul +The links that connect the edge of a network, such as mobile cell sites or exchange equipment, back to the core. Commercially, it also means wholesale capacity bought from another operator for that purpose. + +See also: [RAN](o-r.md#ran), [Leased Line](l-n.md#leased-line). + +### Backlog +An ordered list of everything that might be needed to deliver an outcome, such as a product. The items at the top are the most valuable and the best understood. + +See also: [Backlog Grooming](#backlog-grooming), [Product Owner](o-r.md#product-owner), [User Stories](s-z.md#user-stories). + +### Backlog Grooming +Regular work by the product owner and the team to keep the backlog in order. They add and remove items, prioritise them, and break down the items at the top so they are ready to start. It is also called backlog refinement. + +See also: [Backlog](#backlog), [Definition of Ready](d-f.md#definition-of-ready). + +### Bandwidth +In networking, the maximum rate at which data can cross a path, in bits per second. In signal processing and radio, it means the range of frequencies a signal occupies, in hertz. + +See also: [Latency](l-n.md#latency), [Jitter](g-k.md#jitter). + +### Baseline +An agreed version of an artefact that later work builds on. Changes to a baselined artefact go through change control. + +See also: [Change Control](#change-control), [Configuration Management](#configuration-management). + +### Bash +The GNU Project's Unix shell, a free replacement for the Bourne shell first released in 1989. It is the default shell on most Linux distributions. + +See also: [Sh](s-z.md#sh), [Ksh](g-k.md#ksh), [Csh](#csh), [Shell Scripting](s-z.md#shell-scripting). + +### BASIC +**Beginner's All-purpose Symbolic Instruction Code.** A family of high-level languages designed in 1964 at Dartmouth College to be easy to learn. It was the language most home computers of the 1980s started with. + +See also: [VB](s-z.md#vb). + +### BAU +**Business as usual.** The normal day-to-day running of an organisation, as opposed to projects that bring change. + +### BDD +**Behaviour-Driven Development.** A practice in which the team describes how a system should behave through concrete examples, often in the Given, When, Then form, and uses them as automated tests. + +See also: [Gherkin](g-k.md#gherkin), [Given When Then](g-k.md#given-when-then), [TDD](s-z.md#tdd), [ATDD](#atdd). + +### Bench Test +A test run in the development environment on the part of the system being worked on. + +See also: [Unit Testing](s-z.md#unit-testing), [Developer Integration Test](d-f.md#developer-integration-test). + +### BER +**Basic Encoding Rules.** The original encoding rules for ASN.1, in which each value is written as a type, a length and the value itself. BER allows several encodings of the same value. + +See also: [ASN.1](#asn1), [CER](#cer), [DER](d-f.md#der), [TLV](s-z.md#tlv). + +### Best Practice +A practice or technique that experience shows to work well for a given goal or risk. + +### BFF +**Backend for Frontend.** An architecture pattern in which each kind of client, such as a mobile app or a web app, has its own server-side gateway. The gateway shapes the data and calls that client needs from the services behind it. + +See also: [Microservice](l-n.md#microservice), [API](#api). + +### BGCF +**Breakout Gateway Control Function.** In IMS, the SIP server that decides where a call leaves the IMS network for the circuit-switched telephone network, based on the dialled number. + +See also: [IMS](g-k.md#ims), [MGCF](l-n.md#mgcf), [CSCF](#cscf). + +### BGP +**Border Gateway Protocol.** The routing protocol that exchanges reachability information between autonomous systems on the internet. It is a path vector protocol, and routes are chosen by policy as well as by path. + +See also: [IGP](g-k.md#igp), [OSPF](o-r.md#ospf), [Router](o-r.md#router). + +### Bjarne Stroustrup +The Danish computer scientist who created C++. + +See also: [C++](#c_1). + +### Black-Box Testing +Testing a system through its interfaces, without looking at how it is built. Also called [Functional Testing](d-f.md#functional-testing). + +### Bluetooth +A short-range radio standard in the 2.4 GHz band for connecting devices such as headsets, keyboards and phones into personal area networks. The Bluetooth Special Interest Group manages it. + +See also: [ZigBee](s-z.md#zigbee), [Wi-Fi](s-z.md#wi-fi). + +### BNF +**Backus-Naur Form.** A notation for writing the grammar of a language as a set of production rules. Extended BNF (EBNF) and augmented BNF (ABNF), the variant used in RFCs, add shorthand for repetition and options. + +### BNG +**Broadband Network Gateway.** The router at the edge of a broadband provider's network that terminates subscriber sessions, applies policy and passes their traffic on to the provider's IP network. It is the successor to the BRAS. + +See also: [BRAS](#bras), [PPPoE](o-r.md#pppoe), [DSLAM](d-f.md#dslam). + +### BOOTP +**Bootstrap Protocol.** An early protocol, defined in RFC 951, with which a device gets an IP address and boot information from a server when it starts. DHCP grew out of it and uses the same UDP ports, 67 and 68. + +See also: [DHCP](d-f.md#dhcp), [RARP](o-r.md#rarp). + +### Boston Matrix +A two-by-two chart that sorts a company's products by market share and market growth into stars, cash cows, question marks and dogs. It helps decide where to invest. It is also called the growth-share matrix. + +### Bottom-Up Estimation +Estimating a system by breaking it into small pieces, estimating each one, and adding up the results. + +See also: [Top-Down Estimation](s-z.md#top-down-estimation), [Decomposition Estimation](d-f.md#decomposition-estimation), [Work Breakdown Structure](s-z.md#work-breakdown-structure). + +### BPEL +**Business Process Execution Language.** An OASIS XML language for describing business processes as orchestrations of web service calls. It is also written WS-BPEL. + +See also: [BPMN](#bpmn), [SOA](s-z.md#soa), [WS-BPEL](s-z.md#ws-bpel). + +### BPMN +**Business Process Model and Notation.** A graphical notation, maintained by the Object Management Group, for drawing business processes. Version 2.0 also defines how the diagrams execute. + +See also: [BPEL](#bpel), [UML](s-z.md#uml). + +### BRAS +**Broadband Remote Access Server.** The router that aggregates broadband sessions from DSLAMs and routes them on to the internet service provider's network. Newer designs call it a BNG. + +See also: [BNG](#bng), [DSLAM](d-f.md#dslam), [PPPoE](o-r.md#pppoe). + +### BRI +**Basic Rate Interface.** The ISDN access for homes and small businesses. It has two 64 kbit/s bearer (B) channels for voice or data and one 16 kbit/s D channel for signalling, often written 2B+D. In the UK, BT sold it as ISDN2. + +See also: [ISDN](g-k.md#isdn), [PRI](o-r.md#pri). + +### Broadcast +Sending a message to every receiver on a network segment at once, such as an Ethernet broadcast to all hosts on a LAN. + +See also: [Unicast](s-z.md#unicast), [Multicast](l-n.md#multicast), [Anycast](#anycast). + +### BSC +**Base Station Controller.** In GSM, the node that controls a group of base transceiver stations: it allocates radio channels, manages handovers between them, and concentrates their traffic towards the MSC. + +See also: [BTS](#bts), [MSC](l-n.md#msc), [GSM](g-k.md#gsm), [RNC](o-r.md#rnc). + +### BSS +**Business Support Systems.** The systems a telecoms operator uses to run its business with customers, such as ordering, billing and customer management. They sit beside the operations support systems (OSS). In mobile networks, BSS also stands for base station subsystem: the BTSs and BSCs. + +See also: [OSS](o-r.md#oss). + +### BT 21CN +**BT 21st Century Network.** BT's programme, from the mid-2000s, to replace its separate legacy networks with one IP and MPLS network, using multi-service access nodes (MSANs) in exchanges. The plan to move voice onto it was shelved at the time; the later switch-off of the PSTN finishes that job. + +See also: [MSAN](l-n.md#msan), [NGN](l-n.md#ngn), [PSTN](o-r.md#pstn). + +### BTNUP +**BT National User Part.** BT's variant of ISDN user part signalling. See [IUP](g-k.md#iup). + +### BTS +**Base Transceiver Station.** The radio equipment at a GSM cell site that talks to mobile phones. In UMTS the equivalent is the Node B, and in LTE the eNodeB. + +See also: [BSC](#bsc), [Node B](l-n.md#node-b), [E NodeB](d-f.md#e-nodeb). + +### Bug +A fault in software that makes it behave other than intended. + +See also: [Defect](d-f.md#defect). + +### Build +The process that turns source code and other assets into a runnable system. The word also means the result: a version of the system ready to test. + +See also: [Automated Build](#automated-build), [Build Environment](#build-environment). + +### Build Environment +A separate environment kept for making builds, usually on one or more dedicated build machines. + +See also: [Build Machine](#build-machine), [Development Environment](d-f.md#development-environment). + +### Build Machine +A computer used only to make software builds. + +See also: [Build Environment](#build-environment). + +### Build tool +A tool that automates building software, such as Make, Maven or Gradle. + +See also: [Build](#build). + +### Burndown Chart +A chart that shows the work remaining in an iteration or project against time. A burnup chart shows the work completed instead. + +See also: [Velocity](s-z.md#velocity), [Sprints](s-z.md#sprints). + +### Burst +A short transmission at a high rate, or a group of errors that arrive close together. + +### Business Agility Ownership +Business agility is an organisation's ability to notice change, inside or outside it, and respond quickly enough to keep delivering value to its customers. + +See also: [Agile](#agile). + +### Business Requirement +A high-level goal of the organisation or customer asking for a system: why it is wanted. Also called a [Why Requirement](s-z.md#why-requirement). + +See also: [Requirement](o-r.md#requirement), [Functional Requirement](d-f.md#functional-requirement). + +### Business Schedule +A high-level schedule of a project's main milestones and the business goals tied to them. It sets the top-down limits that the detailed schedule must fit. + +See also: [Detailed Schedule](d-f.md#detailed-schedule), [Milestone](l-n.md#milestone). + +### BYOD +**Bring Your Own Device.** A policy that lets staff use their own laptops, tablets and phones for work, including access to company systems and data. It brings security and support questions that the policy needs to answer. + +## C + +### C Language +A general-purpose, imperative programming language created by Dennis Ritchie at Bell Labs in the early 1970s to write Unix. Its constructs map closely to machine instructions, so it is still the main language for operating systems and embedded software. It is standardised by ISO as ISO/IEC 9899. + +See also: [C++](#c_1), [K & R C](g-k.md#k-r-c), [Embedded systems programming](d-f.md#embedded-systems-programming). + +### C++ {#c_1} +A general-purpose language, created by Bjarne Stroustrup as an extension of C, that adds classes, templates and other abstractions while keeping low-level control of memory. It is standardised by ISO, with new versions every three years. + +See also: [C Language](#c-language), [Bjarne Stroustrup](#bjarne-stroustrup). + +### C-Tag +**Customer VLAN tag.** In IEEE 802.1ad double tagging (Q-in-Q), the inner VLAN tag, set by the customer. The service provider adds an outer S-Tag. + +See also: [S-Tag](s-z.md#s-tag), [VLAN](s-z.md#vlan), [Dot1Q](d-f.md#dot1q). + +### C# {#c_2} +A general-purpose, object-oriented language from Microsoft, created around 2000 for the .NET platform. It also supports functional and generic programming, and is standardised as ECMA-334 and ISO/IEC 23270. + +See also: [.NET](s-z.md#net), [Java](g-k.md#java). + +### CA +**Certificate Authority.** A trusted organisation that issues digital certificates, signing each to bind a public key to the named subject. Browsers trust HTTPS sites because a CA they trust signed the site's certificate. + +See also: [X.509](s-z.md#x509), [TLS](s-z.md#tls), [HTTPS](g-k.md#https). + +### Cacti +An open-source web tool that polls devices, usually over SNMP, and graphs the results with RRDtool, typically to show network traffic and CPU load over time. + +See also: [SNMP](s-z.md#snmp). + +### Cadence +The regular rhythm of a team's work, such as the length of its sprints or its release cycle. + +See also: [Sprints](s-z.md#sprints), [Iteration](g-k.md#iteration), [Timebox](s-z.md#timebox). + +### Calendar Days +The elapsed time an activity takes on the calendar. How staff days turn into calendar days depends on how many people work on it, and when. + +See also: [Staff Days](s-z.md#staff-days). + +### CAMEL +**Customised Applications for Mobile networks Enhanced Logic.** A set of 3GPP standards, based on Intelligent Network ideas, that lets operators add services such as prepaid calling to GSM and UMTS, including while the subscriber is roaming. It uses the CAP protocol. + +See also: [CAP](#cap), [IN](g-k.md#in), [INAP](g-k.md#inap). + +### Camel Case +Writing compound words with no spaces and a capital letter at the start of each word after the first, as in `camelCase`. Pascal case (`PascalCase`) capitalises the first word too. Many coding standards use one or both for identifiers. + +See also: [Snake Case](s-z.md#snake-case), [Hungarian notation](g-k.md#hungarian-notation). + +### CAP +**CAMEL Application Part.** The signalling protocol that CAMEL uses between the switch and the service control point. It runs over TCAP in SS7. + +See also: [CAMEL](#camel), [TCAP](s-z.md#tcap), [SS7](s-z.md#ss7). + +### Capability Maturity Model +**CMM.** A model of software process maturity, developed by the Software Engineering Institute for the US military. It defines five levels: initial, repeatable, defined, managed and optimising. Each level names the key process areas an organisation must have in place. Capability Maturity Model Integration (CMMI) replaced it. + +### Cat 5 +**Category 5 cable.** Twisted-pair cable rated to 100 MHz, used for 100 Mbit/s Ethernet and telephony. Category 5e superseded it in 2001. + +See also: [Cat 5e](#cat-5e), [Cat 6](#cat-6), [Twisted pair](s-z.md#twisted-pair). + +### Cat 5e +**Category 5e cable.** An enhanced Category 5 cable with tighter limits on crosstalk, rated to 100 MHz and good for Gigabit Ethernet up to 100 m. + +See also: [Cat 5](#cat-5), [Cat 6](#cat-6). + +### Cat 6 +**Category 6 cable.** Twisted-pair cable rated to 250 MHz, with stricter crosstalk limits than Cat 5e. It carries 10 Gigabit Ethernet up to about 55 m; Category 6A, rated to 500 MHz, does so up to 100 m. + +See also: [Cat 5](#cat-5), [Cat 5e](#cat-5e), [Ethernet over twisted pair](d-f.md#ethernet-over-twisted-pair). + +### CBOR +**Concise Binary Object Representation.** A binary data format, defined in RFC 8949, based on the JSON data model but designed for small messages and small decoders. It is widely used in constrained IoT devices, with CoAP, and in security tokens. + +See also: [JSON](g-k.md#json), [LwM2M](l-n.md#lwm2m). + +### CCITT +**Comité Consultatif International Téléphonique et Télégraphique.** The former name, until 1993, of the [ITU-T](g-k.md#itu-t). + +### CCS +**Common Channel Signalling.** Telephone signalling carried on a separate channel shared by many voice circuits, rather than in or alongside each circuit. SS7 is the main example. The alternative is channel-associated signalling (CAS). + +See also: [SS7](s-z.md#ss7), [ISUP](g-k.md#isup). + +### CCTA +**Central Computer and Telecommunications Agency.** A former UK government agency that supported departments' computing and telecoms. It created ITIL and PRINCE. + +See also: [ITIL](g-k.md#itil), [PRINCE2](o-r.md#prince2). + +### CDMA +**Code-Division Multiple Access.** A channel access method in which many transmitters share the same frequency band at the same time, each spread with its own code. It is the basis of cdmaOne, CDMA2000 and, as wideband CDMA, UMTS. + +See also: [CDMA2000](#cdma2000), [W-CDMA](s-z.md#w-cdma), [OFDMA](o-r.md#ofdma). + +### CDMA2000 +The 3G family of mobile standards developed by 3GPP2 as the successor to cdmaOne (IS-95), used mainly in North America and South Korea. It competed with UMTS. + +See also: [CDMA](#cdma), [UMTS](s-z.md#umts). + +### CDR +**Call Detail Record.** A record made by a switch or other network element for each call or session, with details such as the numbers, start time, duration and outcome. CDRs feed billing, fraud detection and reporting. + +See also: [Mediation](l-n.md#mediation). + +### CE +**Customer Edge.** The customer's router that connects to the service provider's provider edge (PE) router in an MPLS VPN. It exchanges routes with the PE, statically or with a routing protocol. + +See also: [VRF](s-z.md#vrf), [L3VPN](l-n.md#l3vpn), [NPE](l-n.md#npe). + +### CER +**Canonical Encoding Rules.** A restricted form of BER for ASN.1 that allows only one encoding for each value, so that encoded data can be compared or signed. + +See also: [BER](#ber), [DER](d-f.md#der), [ASN.1](#asn1). + +### Ceremonies +The regular meetings of an agile process, such as sprint planning, the daily stand-up, the review and the retrospective. + +See also: [Daily Scrum](d-f.md#daily-scrum), [Sprint Planning](s-z.md#sprint-planning), [Sprint retrospective](s-z.md#sprint-retrospective). + +### CESG +**Communications-Electronics Security Group.** The part of GCHQ that was the UK government's technical authority for information assurance. Its role passed to the National Cyber Security Centre in 2016. + +See also: [GCHQ](g-k.md#gchq), [NCSC](l-n.md#ncsc), [IA](g-k.md#ia). + +### CFi +**Canonical Format Indicator.** A one-bit field in the IEEE 802.1Q VLAN tag that showed whether MAC addresses were in canonical form. It is always 0 on Ethernet, and later revisions renamed it the drop eligible indicator. + +See also: [Dot1Q](d-f.md#dot1q), [VLAN](s-z.md#vlan). + +### CGI +**Common Gateway Interface.** A standard way for a web server to run an external command to answer a request, passing it the request details and returning its output as the page. + +See also: [HTTP](g-k.md#http). + +### Change Control +The part of change management that decides which artefacts are controlled and makes sure changes to them are proposed, assessed and approved before they are made. The term is also used for change management as a whole. + +See also: [Change Control Board](#change-control-board), [Change Request](#change-request), [Explicit Change Control](d-f.md#explicit-change-control), [Implicit Change Control](g-k.md#implicit-change-control). + +### Change Control Board +**CCB.** The group that decides on change requests to artefacts under change control. + +See also: [Change Control](#change-control), [Change Request](#change-request). + +### Change Control Plan +A plan that sets out what change control applies to which project artefacts. + +See also: [Change Control](#change-control). + +### Change Management +Managing requested changes to a project's scope, features or artefacts in a controlled way. + +See also: [Change Control](#change-control), [Configuration Management](#configuration-management). + +### Change Request +**CR.** A request to change something under change control, usually to add, change or remove a requirement, or to change the project plan. + +See also: [Change Control Board](#change-control-board), [Software Change Request](s-z.md#software-change-request). + +### CHAP +**Challenge-Handshake Authentication Protocol.** A PPP authentication protocol, defined in RFC 1994. The server sends a challenge and the client answers with a hash of the challenge and a shared secret, so the secret never crosses the link. It is safer than PAP. + +See also: [PAP](o-r.md#pap), [PPP](o-r.md#ppp), [EAP](d-f.md#eap). + +### Chrome OS +Google's operating system, based on the Linux kernel, that uses the Chrome browser as its main interface and runs mostly web applications. + +See also: [Linux](l-n.md#linux), [Android](#android). + +### Circuit Switched +A network in which a dedicated path is set up between the two ends before they communicate, and held for the whole call, as in the traditional telephone network. + +See also: [Packet Switched](o-r.md#packet-switched), [PSTN](o-r.md#pstn), [TDM](s-z.md#tdm). + +### Class 4 Softswitch +A softswitch that routes large volumes of voice calls between carriers, the VoIP equivalent of a class 4 (trunk) exchange. What matters most is protocol support and conversion, transcoding and call capacity. + +See also: [Softswitch](s-z.md#softswitch), [Class 5 Softswitch](#class-5-softswitch). + +### Class 5 Softswitch +A softswitch that serves end users, the VoIP equivalent of a class 5 (local) exchange. It provides subscriber features such as IP PBX functions, call centres and voicemail. + +See also: [Softswitch](s-z.md#softswitch), [Class 4 Softswitch](#class-4-softswitch). + +### Class Model +A model of the static structure of an object-oriented system: its classes and how they relate. + +See also: [UML](s-z.md#uml), [OO](o-r.md#oo). + +### CLF +**Connectivity Session Location and Repository Function.** In the ETSI TISPAN next-generation network, the function that records each subscriber's access session, linking their IP address to their line and location. It is not to be confused with the IMS subscriber location function (SLF), which finds the right HSS for a user when there are several. + +See also: [NGN](l-n.md#ngn), [HSS](g-k.md#hss), [IMS](g-k.md#ims). + +### CMDB +**Configuration Management Database.** A store of the configuration items in an IT estate and the relationships between them, used in ITIL to understand the effect of changes and incidents. + +See also: [Configuration Item](#configuration-item), [ITIL](g-k.md#itil). + +### CNG +**Comfort Noise Generation.** Adding artificial background noise at the receiving end of a call during silences, when voice activity detection has stopped the sender transmitting. Without it, the line goes dead quiet and callers think the call has dropped. + +See also: [VAD](s-z.md#vad), [VoIP](s-z.md#voip). + +### COBOL +**Common Business-Oriented Language.** An English-like, compiled language designed in 1959 for business data processing. A great deal of banking and government software on mainframes is still written in it. + +See also: [Fortran](d-f.md#fortran). + +### Code and Fix Lifecycle +Developing a system from a rough idea through repeated rounds of coding and fixing, with little planning or design, until it seems ready to release. + +See also: [Lifecycle](l-n.md#lifecycle), [Waterfall](s-z.md#waterfall). + +### Codecs +A codec (coder-decoder) is a device or piece of software that encodes a signal or data stream for transmission or storage, usually compressing it. It also decodes it again for use. + +See also: [Audio Codecs](#audio-codecs), [MPEG](l-n.md#mpeg). + +### Coding +Writing the source code that defines how software behaves; the core activity of construction. + +See also: [Construction](#construction), [Source Code](s-z.md#source-code). + +### Coding Standard +See [Construction Standard](#construction-standard). + +### CoE +**Centre of Excellence.** A team or group that provides leadership, good practice, support and training in one area, such as a technology or a skill, across an organisation. + +### COFDM +**Coded Orthogonal Frequency-Division Multiplexing.** OFDM with forward error correction and interleaving added, so the signal survives multipath fading. Digital terrestrial TV (DVB-T) and DAB use it. + +See also: [OFDMA](o-r.md#ofdma), [DTT](d-f.md#dtt). + +### Collaboration Model +A model, such as a UML communication diagram, that shows a set of objects or roles and the messages they exchange. + +See also: [Sequence Model](s-z.md#sequence-model), [UML](s-z.md#uml). + +### Collaborative Construction +A way of building software in which a small group of developers work closely together on the same functionality. They talk often and informally, and share ownership of the code and its tests. + +See also: [Pair Programming](o-r.md#pair-programming), [Mob Programming](l-n.md#mob-programming), [Collective code ownership](#collective-code-ownership). + +### Collective code ownership +The convention that anyone on the team may change any part of the code, to finish a task, fix a defect or improve its structure. + +See also: [XP](s-z.md#xp), [Pair Programming](o-r.md#pair-programming). + +### COLO +**Colocation.** Housing equipment in another party's building, typically placing a provider's equipment in a carrier's exchange or a data centre. + +### Compatibility Test +See [Configuration Test](#configuration-test). + +### Compiled Language +A programming language whose usual implementations translate source code ahead of time into machine code, rather than interpret it. The line is blurred: many languages compile to bytecode that a virtual machine then interprets or compiles just in time. + +See also: [Compiler](#compiler), [Interpreted Language](g-k.md#interpreted-language). + +### Compiler +Software that translates code from one language, usually a high-level language, into another, usually machine code or bytecode. A typical compiler has a front end, a middle end and a back end. A cross-compiler produces code for a different machine from the one it runs on. + +See also: [Compiler Front end](#compiler-front-end), [Compiler Middle end](#compiler-middle-end), [Compiler Back end](#compiler-back-end), [Compiler preprocessor](#compiler-preprocessor), [Machine code](l-n.md#machine-code). + +### Compiler Back end +The stage of a compiler that turns the optimised intermediate representation into code for one target processor: choosing instructions, allocating registers and scheduling. + +See also: [Compiler](#compiler), [Compiler Middle end](#compiler-middle-end). + +### Compiler Front end +The stage of a compiler that reads the source language: it checks syntax and semantics, reports errors, and produces an intermediate representation for the later stages. + +See also: [Compiler](#compiler), [Compiler Middle end](#compiler-middle-end). + +### Compiler Middle end +The stage of a compiler that optimises the intermediate representation in ways that do not depend on the target processor, such as removing dead code and propagating constants. + +See also: [Compiler](#compiler), [Compiler Front end](#compiler-front-end), [Compiler Back end](#compiler-back-end). + +### Compiler preprocessor +A tool that transforms source code before compilation, for example the C preprocessor, which expands macros, includes files and handles conditional compilation. + +See also: [Compiler](#compiler), [C Language](#c-language). + +### Component +A part of a software system with a defined interface and responsibility. + +See also: [Component Test](#component-test). + +### Component Test +A test of one software component on its own, apart from the rest of the system. + +See also: [Unit Testing](s-z.md#unit-testing), [Integration Test](g-k.md#integration-test). + +### Cone of Uncertainty +The observation that estimates made early in a project can be wrong by a large factor either way. The range narrows as the project goes on and decisions are made. + +See also: [Estimation](d-f.md#estimation), [Progressive Elaboration](o-r.md#progressive-elaboration). + +### Configuration Item +**CI.** An artefact, or a group of them, that is placed under configuration management and tracked as a unit. + +See also: [Configuration Management](#configuration-management), [CMDB](#cmdb). + +### Configuration Management +**CM.** Identifying, recording, releasing and controlling the versions of a system's artefacts so that its state is known at every point. + +See also: [Configuration Item](#configuration-item), [Version Control](s-z.md#version-control), [Software Configuration Management](s-z.md#software-configuration-management). + +### Configuration Test +A test of how a system behaves on different platforms, settings and environments. + +### Construction +Turning a design into working software: detailed design, coding, unit testing, integration and debugging. + +See also: [Coding](#coding), [Construction Standard](#construction-standard). + +### Construction Environment +See [Development Environment](d-f.md#development-environment). + +### Construction Lead +The person responsible for construction on a project: integration, builds, the development environment, technology problems and deployment. + +### Construction Standard +The conventions and style developers follow when writing a system's source code. Also called a coding standard. + +See also: [Coding Standard](#coding-standard). + +### Construction Test Environment +See [Local Test Environment](l-n.md#local-test-environment). + +### Construction Testing +The tests a developer runs while building a component, to check changes both in the component and in the system around it. + +See also: [Unit Testing](s-z.md#unit-testing), [Developer Integration Test](d-f.md#developer-integration-test). + +### Continuous Deployment +Releasing every change that passes the automated pipeline straight to production, so that code reaches users soon after it is written. + +See also: [Continuous Integration](#continuous-integration), [DevOps](d-f.md#devops). + +### Continuous Integration +**CI.** Merging every developer's changes into a shared mainline several times a day, with an automated build and tests on each merge. The product is then always in a releasable state. + +See also: [Automated Build](#automated-build), [Continuous Deployment](#continuous-deployment). + +### Control Plane +The part of a network device or network that decides where traffic goes: running routing protocols and building the tables that the data plane uses to forward packets. + +See also: [Data Plane](d-f.md#data-plane), [Management Plane](l-n.md#management-plane), [User Plane](s-z.md#user-plane), [SDN](s-z.md#sdn). + +### Copyleft +Licensing that lets anyone copy, change and share a work on condition that copies and derived works are shared under the same terms. The GPL is the best-known copyleft licence. + +See also: [GPL](g-k.md#gpl), [GNU](g-k.md#gnu). + +### CoS +**Class of Service.** A marking in a frame or packet that puts it into a traffic class, so the network can give some classes priority over others. + +See also: [QoS](o-r.md#qos), [PCP](o-r.md#pcp), [DSCP](d-f.md#dscp). + +### COTS +**Commercial off-the-shelf.** Products bought ready-made, and configured or adapted, rather than built to order. + +See also: [Mil-COTS](l-n.md#mil-cots). + +### CPE +**Customer Premises Equipment.** Equipment at the customer's site that connects to the operator's network at the demarcation point, such as a router, modem or phone. + +See also: [NTU](l-n.md#ntu). + +### CPM +**Critical Path Method.** A scheduling technique that finds the longest chain of dependent activities in a project. That chain sets the shortest possible duration, and any delay on it delays the end date. + +See also: [PERT chart](o-r.md#pert-chart), [Gantt chart](g-k.md#gantt-chart). + +### CPS +**Carrier Pre-Selection.** A UK telephone service that sent a customer's calls through another carrier's network automatically, without dialling a prefix, while the line stayed with the incumbent. + +See also: [WLR](s-z.md#wlr), [LCR](l-n.md#lcr). + +### CRC +**Cyclic Redundancy Check.** An error-detecting code calculated as the remainder of a polynomial division of the data. The sender appends it; the receiver recalculates it and treats any mismatch as corruption. Ethernet's frame check sequence is a CRC-32. + +See also: [FCS](d-f.md#fcs), [Hash Function](g-k.md#hash-function). + +### CRC Cards +**Class-Responsibility-Collaborator cards.** Index cards used in object-oriented design sessions, one for each class, listing what the class is responsible for and which classes it works with. + +See also: [OO](o-r.md#oo), [Class Model](#class-model). + +### CSCF +**Call Session Control Function.** The SIP servers at the heart of IMS. The proxy CSCF (P-CSCF) is the device's first contact with the network. The interrogating CSCF (I-CSCF) finds the right serving CSCF for a user. The serving CSCF (S-CSCF) registers users and controls their sessions. + +See also: [IMS](g-k.md#ims), [SIP](s-z.md#sip), [HSS](g-k.md#hss). + +### Csh +The C shell, a Unix shell written by Bill Joy at Berkeley in the late 1970s, with a syntax modelled on C. Tcsh is its improved successor. + +See also: [Tcsh](s-z.md#tcsh), [Bash](#bash), [Sh](s-z.md#sh). + +### CSI +**Customer Site Interconnect.** A physical link between an operator's network and a customer's site or another operator's equipment. + +See also: [Leased Line](l-n.md#leased-line). + +### CSMA +**Carrier-Sense Multiple Access.** A media access method in which a device listens for traffic on a shared medium and transmits only when it is idle. Classic Ethernet added collision detection (CSMA/CD); Wi-Fi uses collision avoidance (CSMA/CA). + +See also: [MAC](l-n.md#mac), [Wi-Fi](s-z.md#wi-fi). + +### CSS +**Cascading Style Sheets.** The language that describes how HTML documents are presented, such as layout, colours and fonts, keeping presentation apart from content. + +See also: [XML](s-z.md#xml), [W3C](s-z.md#w3c). + +### CUE +**Configure Unify Execute.** An open-source language for validating, templating and generating configuration and data. It treats types and values as one thing, so a schema, a constraint and concrete data can be combined and checked in the same way. + +See also: [JSON](g-k.md#json), [YAML](s-z.md#yaml). + +### Customer Development +A four-step framework from Steve Blank (discovery, validation, creation and building the company) for testing assumptions about a product and its market by experiment. + +See also: [MVP](l-n.md#mvp). + +### CVSD +**Continuously Variable Slope Delta modulation.** A speech coding method that sends one bit per sample, saying whether the signal went up or down, with a step size that adapts to the signal. It is robust against bit errors and is used in military radio and Bluetooth voice. + +See also: [PCM](o-r.md#pcm), [Audio Codecs](#audio-codecs). diff --git a/content/glossary/d-f.md b/content/glossary/d-f.md new file mode 100644 index 0000000..2418d7f --- /dev/null +++ b/content/glossary/d-f.md @@ -0,0 +1,757 @@ +--- +title: Glossary, D to F +--- + +# D to F + +## D + +### DAD +**Disciplined Agile Delivery.** A process decision framework by Scott Ambler and Mark Lines. It combines practices from Scrum, XP, Lean and agile modelling, and helps teams choose how to work across the whole delivery lifecycle, including at scale. + +See also: [Agile](a-c.md#agile), [SAFe](s-z.md#safe), [LeSS](l-n.md#less). + +### Daily Meeting +A short meeting held at the same time each day, at which the team coordinates its work. Also called the daily stand-up. + +See also: [Daily Scrum](#daily-scrum), [Three Questions](s-z.md#three-questions). + +### Daily Scrum +Scrum's daily stand-up: a meeting of 15 minutes or less in which the team reviews progress towards the sprint goal and plans the next day. + +See also: [Daily Meeting](#daily-meeting), [Scrum](s-z.md#scrum). + +### Dark Fibre +Optical fibre that is installed but not lit by its owner's equipment. Customers lease it and attach their own equipment, so they control the capacity and technology rather than buying a bandwidth service. + +See also: [Leased Line](l-n.md#leased-line). + +### DASS1 +**Digital Access Signalling System 1.** An early BT protocol for ISDN access in the UK, replaced by DASS2 and long obsolete. + +See also: [DASS2](#dass2), [ISDN](g-k.md#isdn). + +### DASS2 +**Digital Access Signalling System 2.** BT's signalling protocol for ISDN primary rate lines (2 Mbit/s, 30 channels), designed before Q.931 was finished. Standard EuroISDN (Q.931) access has replaced it. + +See also: [DASS1](#dass1), [Q.931](o-r.md#q931), [PRI](o-r.md#pri), [DPNSS](#dpnss). + +### Data modelling +Analysing the data a business uses: identifying the entities, their attributes and the relationships between them. + +See also: [RDBMS](o-r.md#rdbms), [Model](l-n.md#model). + +### Data Plane +The part of a network device that forwards packets, using tables built by the control plane. Also called the forwarding plane or [User Plane](s-z.md#user-plane). + +See also: [Control Plane](a-c.md#control-plane), [Management Plane](l-n.md#management-plane). + +### Database Lead +On projects with large or critical databases, the person responsible for the design and construction of the database parts of the system. + +### Data Warehouse +A central store of current and historical data, integrated from several operational systems and organised for reporting and analysis rather than for transactions. + +See also: [ETL](#etl), [RDBMS](o-r.md#rdbms). + +### DCE +**Data Circuit-terminating Equipment.** The device that connects a terminal or computer (the DTE) to a transmission line, such as a modem. + +See also: [DTE](#dte). + +### DDK +**Driver Development Kit.** The tools, libraries, headers and documentation needed to write device drivers for an operating system. + +See also: [Driver](#driver), [SDK](s-z.md#sdk). + +### DDOS +**Distributed Denial of Service.** An attack that floods a target with traffic from many sources at once, often a botnet, to make it unavailable to legitimate users. Because the traffic comes from everywhere, blocking one source does not stop it. + +See also: [Firewall](#firewall), [IPS](g-k.md#ips). + +### Decomposition Estimation +Estimating each part of a system after breaking it down. See [Bottom-Up Estimation](a-c.md#bottom-up-estimation). + +### Defect +A flaw in a system, process or artefact that makes it fail to meet its specification, a standard or a reasonable expectation. + +See also: [Bug](a-c.md#bug), [Defect Report](#defect-report), [Defect Management](#defect-management). + +### Defect Management +Recording, prioritising, tracking and closing defects so that none are lost. + +See also: [Defect](#defect), [Issue tracker](g-k.md#issue-tracker). + +### Defect Report +A record asking for an artefact to be changed because it does not conform to a requirement or standard, or because it fails. + +See also: [Defect](#defect). + +### Definition of Done +**DoD.** A list, agreed by the team, of what must be true before a piece of work, such as a user story, counts as finished. It usually includes tests passing, review and documentation. + +See also: [Definition of Ready](#definition-of-ready), [User Stories](s-z.md#user-stories). + +### Definition of Ready +**DoR.** Criteria a backlog item must meet before the team takes it into an iteration, such as clear acceptance criteria and no blocking dependencies. Many teams base it on INVEST. + +See also: [Definition of Done](#definition-of-done), [INVEST](g-k.md#invest), [Backlog Grooming](a-c.md#backlog-grooming). + +### Deliverable +An artefact, or set of artefacts, that a project or piece of work hands over as its output. + +See also: [Artefact](a-c.md#artefact), [Work Product](s-z.md#work-product). + +### Delphi +Embarcadero's (originally Borland's) development environment for Object Pascal, an object-oriented descendant of Pascal. The language itself is often called Delphi too. + +See also: [Pascal](o-r.md#pascal). + +### Deployment +Installing a system and making it ready for use, including any integration and configuration for the particular site. + +See also: [Deployment Plan](#deployment-plan), [Release](o-r.md#release). + +### Deployment Lead +On projects with complex deployment needs, the person who plans and oversees deployment, and often operations and maintenance. + +### Deployment Plan +A plan for releasing a system, covering the target platforms, the configuration to release and the steps to follow. + +See also: [Deployment](#deployment), [Release Management](o-r.md#release-management). + +### DER +**Distinguished Encoding Rules.** A restricted form of BER that allows exactly one encoding for each ASN.1 value. It is used where encodings must be unique, above all for data that is signed, such as X.509 certificates. + +See also: [BER](a-c.md#ber), [CER](a-c.md#cer), [ASN.1](a-c.md#asn1), [X.509](s-z.md#x509). + +### DES +**Data Encryption Standard.** A symmetric block cipher from IBM, published as a US federal standard in 1977, with a 64-bit block and a 56-bit key. The short key made it breakable by brute force by the late 1990s, and AES replaced it. + +See also: [Triple DES](s-z.md#triple-des), [AES](a-c.md#aes). + +### Design +Software design: working out the structure of a system and the models and plans for implementing its requirements. + +See also: [High Level Design](g-k.md#high-level-design), [Low Level Design](l-n.md#low-level-design), [Architecture](a-c.md#architecture). + +### Design Lead +The person responsible for a system's architecture and for overseeing design work. + +### Design Pattern +A general, reusable solution to a problem that keeps coming up in software design. A pattern is a description to adapt, not finished code. The Gang of Four book catalogued the best-known object-oriented patterns. + +See also: [GoF](g-k.md#gof), [Pattern](o-r.md#pattern), [Antipattern](a-c.md#antipattern). + +### Design to Tools +Deciding what goes into a system by what existing tools support directly, rather than by what users need. + +### Desk Check +An informal review in which the author asks one or more colleagues to read an artefact and look for defects. + +See also: [Review](o-r.md#review), [Walkthrough](s-z.md#walkthrough). + +### Detailed Design +Design work below the architecture, covering parts of both high-level and low-level design. + +See also: [High Level Design](g-k.md#high-level-design), [Low Level Design](l-n.md#low-level-design). + +### Detailed Schedule +A fine-grained schedule of tasks, effort, people and dependencies, usually built bottom-up from a work plan. It often covers only the next few weeks and rolls forward. + +See also: [Business Schedule](a-c.md#business-schedule), [Rolling Wave Planning](o-r.md#rolling-wave-planning), [Project Headlights](o-r.md#project-headlights). + +### Developer +A software engineer, especially when doing design and construction. + +### Developer Integration Test +**DIT.** An integration test that a developer runs in the system test environment after a project build, before releasing new functionality. + +See also: [Integration Test](g-k.md#integration-test). + +### Development Environment +The hardware, software and tools in which developers build and test software. + +See also: [Local Development Environment](l-n.md#local-development-environment), [IDE](g-k.md#ide). + +### Development process +The set of activities a team follows to develop software. + +See also: [Lifecycle](l-n.md#lifecycle), [SDLC](s-z.md#sdlc). + +### DevOps +A way of working that brings development and operations together, sharing responsibility for delivering and running software. It relies on automation of builds, tests, deployment and monitoring. + +See also: [Continuous Integration](a-c.md#continuous-integration), [Continuous Deployment](a-c.md#continuous-deployment). + +### DHCP +**Dynamic Host Configuration Protocol.** The protocol a device uses to get an IP address and other network settings, such as the gateway and DNS servers, from a server when it joins a network. + +See also: [BOOTP](a-c.md#bootp), [DNS](#dns). + +### Diagram +A graphical representation of a system, process or other information. + +### DLE +**Digital Local Exchange.** A digital telephone exchange that connects subscribers' lines, either directly or through remote concentrators. In the UK these were System X and AXE 10 exchanges. + +See also: [SystemX](s-z.md#systemx), [MDF](l-n.md#mdf), [Local Loop](l-n.md#local-loop). + +### DLP +**Data Link Protocol.** Any protocol at the data link layer (layer 2) of the OSI model, such as Ethernet, Token Ring, FDDI or PPP. DLP also commonly stands for data loss prevention. + +See also: [L2](l-n.md#l2). + +### DMZ +**Demilitarised Zone.** A network segment that sits between the internet and an organisation's internal network, holding the services that outsiders need to reach, such as web and mail servers. Firewalls on both sides limit what each zone can reach. + +See also: [Firewall](#firewall). + +### DN +**Directory Number.** A telephone number: the digits that identify a subscriber's line or device and route calls to it. + +See also: [E.164](#e164). + +### DNB +A Dun & Bradstreet business file: a company's credit and identity record from Dun & Bradstreet. + +### DNS +**Domain Name System.** The internet's distributed, hierarchical naming system. Its main job is to translate names such as `example.com` into IP addresses, but it holds many other kinds of record. + +See also: [Domain Name](#domain-name), [FQDN](#fqdn), [DNS - A](#dns-a), [DNS Spoofing](#dns-spoofing). + +### DNS - A {#dns-a} +**Address record.** A DNS record that maps a name to an IPv4 address. + +See also: [DNS - AAAA](#dns-aaaa), [DNS](#dns). + +### DNS - AAAA {#dns-aaaa} +A DNS record that maps a name to an IPv6 address. + +See also: [DNS - A](#dns-a), [IPv6](g-k.md#ipv6). + +### DNS - CNAME {#dns-cname} +**Canonical name record.** A DNS record that makes one name an alias for another; the lookup carries on with the target name. + +See also: [DNS - DNAME](#dns-dname). + +### DNS - DNAME {#dns-dname} +A DNS record that makes a name, and every name under it, an alias for another domain. A CNAME aliases only the exact name. + +See also: [DNS - CNAME](#dns-cname). + +### DNS - SRV {#dns-srv} +**Service record.** A DNS record that gives the host and port for a named service, such as SIP or XMPP, together with priority and weight. + +See also: [SIP](s-z.md#sip), [XMPP](s-z.md#xmpp). + +### DNS - TXT {#dns-txt} +A DNS record that holds arbitrary text. It now mostly carries machine-readable data, such as SPF, DKIM and DMARC policies for email and domain ownership proofs. + +### DNS Spoofing +An attack that puts false records into a DNS resolver's cache, so that it sends users to the wrong address, usually one the attacker controls. Also called DNS cache poisoning. + +See also: [DNS](#dns), [ARP spoofing](a-c.md#arp-spoofing). + +### DoD +See [Definition of Done](#definition-of-done). + +### DoR +See [Definition of Ready](#definition-of-ready). + +### Docker +A platform for building and running software in containers: packages that hold an application and its dependencies and run in isolation on a shared operating system kernel. + +See also: [VM](s-z.md#vm). + +### Document Collaboration +Tools that let several people work on the same document at once, from different places, to reach one final version. Wikis, Confluence and SharePoint are examples. + +See also: [Wiki](s-z.md#wiki). + +### Domain Name +A name registered in the DNS, such as `example.co.uk`, that identifies an area of administrative control on the internet. Names form a hierarchy under the unnamed root: top-level domains, then second-level domains, then subdomains. + +See also: [DNS](#dns), [FQDN](#fqdn). + +### Dot1Q +**IEEE 802.1Q.** The standard for VLANs on Ethernet. It adds a 4-byte tag to each frame with a 12-bit VLAN identifier and a 3-bit priority (802.1p). + +See also: [VLAN](s-z.md#vlan), [Dot1Q trunking](#dot1q-trunking), [PCP](o-r.md#pcp). + +### Dot1Q trunking +Carrying several VLANs over one link between switches. Each frame is tagged with its VLAN ID as it enters the trunk. The switch at the other end uses the tag to deliver it to ports in the same VLAN. + +```mermaid +flowchart LR + A10[Port, VLAN 10] --> S1[Switch 1] + A20[Port, VLAN 20] --> S1 + S1 == "trunk: frames tagged 10 or 20" ==> S2[Switch 2] + S2 --> B10[Port, VLAN 10] + S2 --> B20[Port, VLAN 20] +``` + +[[CAPTION:Figure]] Two VLANs sharing an 802.1Q trunk. + +See also: [Dot1Q](#dot1q), [VLAN](s-z.md#vlan). + +### Downstream +In a project, the later activities and artefacts, such as coding, testing and deployment. In networking, the direction towards the customer. + +See also: [Upstream](s-z.md#upstream). + +### DP +**Distribution Point.** In a UK access network, the point near the customer, often on a telegraph pole, where the drop wire to the premises joins the cable from the exchange. In fibre networks, the point where a fibre splits towards several premises. + +See also: [Local Loop](l-n.md#local-loop), [PCP](o-r.md#pcp). + +### DPI +**Deep Packet Inspection.** Examining the contents of packets, beyond the IP and transport headers, to classify, block, shape or log traffic. Firewalls, intrusion prevention and traffic management use it. + +See also: [Firewall](#firewall), [IPS](g-k.md#ips), [Packet sniffing](o-r.md#packet-sniffing). + +### DPNSS +**Digital Private Network Signalling System.** A BT-defined protocol for linking PBXs over digital private circuits, with a common set of features across vendors. QSIG is the international equivalent. + +See also: [QSIG](o-r.md#qsig), [DASS2](#dass2). + +### DQ +**Data Quality.** How accurate, complete, consistent and timely data is for its purpose. + +### Draft +An artefact under version control but not yet under change control. + +See also: [Baseline](a-c.md#baseline). + +### Driver +Software that lets an operating system and applications use a particular device, hiding the details of the hardware behind a standard interface. + +See also: [DDK](#ddk), [Kernel](g-k.md#kernel). + +### DSCP +**Differentiated Services Code Point.** A 6-bit field in the IP header that marks a packet's traffic class, so routers can give it the right treatment under DiffServ quality of service. + +See also: [QoS](o-r.md#qos), [CoS](a-c.md#cos). + +### DSDM +**Dynamic Systems Development Method.** An agile framework from the 1990s, built on rapid application development, that fixes time and cost and varies scope. It is now called the DSDM agile project framework. + +See also: [Agile development](a-c.md#agile-development), [RAD](o-r.md#rad). + +### DSL +**Digital Subscriber Line.** A family of technologies that carry digital data over copper telephone lines, using frequencies above voice. ADSL and VDSL are the most common. + +See also: [ADSL](a-c.md#adsl), [SDSL](s-z.md#sdsl), [VDSL](s-z.md#vdsl), [DSLAM](#dslam). + +### DSLAM +**Digital Subscriber Line Access Multiplexer.** The equipment in an exchange or street cabinet that terminates many customers' DSL lines and combines their traffic onto one high-speed link. + +See also: [DSL](#dsl), [MSAN](l-n.md#msan), [BRAS](a-c.md#bras). + +### DTE +**Data Terminal Equipment.** The device at the end of a data link that is the source or destination of data, such as a computer or terminal. It connects to the line through a DCE. + +```mermaid +flowchart LR + A[DTE: computer] --- B[DCE: modem] --- C((Line)) --- D[DCE: modem] --- E[DTE: computer] +``` + +[[CAPTION:Figure]] DTEs connected through DCEs. + +See also: [DCE](#dce). + +### DTLS +**Datagram Transport Layer Security.** A version of TLS for datagram transports such as UDP, giving the same confidentiality, integrity and authentication. It is used by CoAP and LwM2M in IoT and by WebRTC. The current version is DTLS 1.3, in RFC 9147. + +See also: [TLS](s-z.md#tls), [UDP](s-z.md#udp), [LwM2M](l-n.md#lwm2m). + +### DTMF +**Dual-Tone Multi-Frequency.** Telephone signalling in which each key sends two tones at once, one from a low group and one from a high group. It is standardised as ITU-T Q.23, and BT calls it MF4. + +See also: [IVR](g-k.md#ivr), [PSTN](o-r.md#pstn). + +### DTT +**Digital Terrestrial Television.** Television broadcast digitally from ground-based transmitters, such as Freeview in the UK. It fits several channels into the spectrum one analogue channel used. + +See also: [DTV](#dtv), [COFDM](a-c.md#cofdm). + +### DTV +**Digital Television.** Television sent as digital signals rather than analogue, by terrestrial, satellite, cable or IP networks. + +See also: [DTT](#dtt), [IPTV](g-k.md#iptv). + +### Duplex +A link that can carry communication in both directions. In full duplex both sides can send at once; in half duplex they take turns. A simplex link carries one direction only. + +```mermaid +flowchart LR + subgraph Simplex + S1[A] --> S2[B] + end + subgraph "Half duplex: one way at a time" + H1[A] <-.-> H2[B] + end + subgraph "Full duplex: both ways at once" + F1[A] --> F2[B] + F2 --> F1 + end +``` + +[[CAPTION:Figure]] Simplex, half duplex and full duplex. + +See also: [Full duplex](#full-duplex), [Half Duplex](g-k.md#half-duplex), [Simplex](s-z.md#simplex). + +### DVSR +**Dynamically Verified Static Routing.** A Redback (later Ericsson) routing feature: a static route that the router adds to its table only while regular pings show the next hop is reachable. + +See also: [Router](o-r.md#router). + +## E + +### E NodeB +**Evolved Node B (eNodeB, eNB).** The LTE base station. Unlike a UMTS Node B, it has no separate controller: it handles radio resource management and handover itself, and connects directly to the core. + +See also: [E-UTRAN](#e-utran), [Node B](l-n.md#node-b), [MME](l-n.md#mme), [LTE (4G)](l-n.md#lte-4g). + +### E-UTRAN +**Evolved UMTS Terrestrial Radio Access Network.** The LTE radio access network: eNodeBs and the E-UTRA air interface, which uses OFDMA downstream and SC-FDMA upstream. + +See also: [E NodeB](#e-nodeb), [UTRAN](s-z.md#utran), [LTE (4G)](l-n.md#lte-4g). + +### E.164 {#e164} +The ITU-T recommendation for the international public telephone numbering plan. An E.164 number has at most 15 digits, starting with the country code, and is written with a leading `+`. + +See also: [DN](#dn). + +### EAD +**Ethernet Access Direct.** Openreach's point-to-point fibre Ethernet circuit, used to connect business sites and for backhaul, at speeds up to 10 Gbit/s. + +See also: [EoFTTC](#eofttc), [Leased Line](l-n.md#leased-line), [Backhaul](a-c.md#backhaul). + +### EAP +**Extensible Authentication Protocol.** An authentication framework, defined in RFC 3748, that carries many authentication methods, such as EAP-TLS and PEAP. IEEE 802.1X uses it for network access control on Wi-Fi and wired networks. + +See also: [PEAP](o-r.md#peap), [WPA2](s-z.md#wpa2), [Radius](o-r.md#radius). + +### Earned Value +**EV.** A measure of progress that compares the value of the work completed with the work planned and its actual cost, to show schedule and cost variance. + +See also: [Earned Value Management](#earned-value-management). + +### Earned Value Management +**EVM.** Managing a project using earned value measures. + +See also: [Earned Value](#earned-value). + +### Echo +A delayed reflection of a signal. On telephone calls it comes from hybrids that convert between 2-wire and 4-wire circuits, or from a loudspeaker feeding back into a microphone. Delay makes it more noticeable. + +See also: [Echo cancellation](#echo-cancellation), [Sidetone](s-z.md#sidetone). + +### Echo cancellation +Removing echo from a call by modelling the echo path and subtracting an estimate of the echo from the incoming signal. It replaced echo suppression, which muted the return path while the far end was talking. Line echo cancellers handle network echo; acoustic echo cancellers handle loudspeaker-to-microphone echo. + +See also: [Echo](#echo), [Echo Cancellation - G.168](#echo-cancellation-g168). + +### Echo Cancellation - G.168 {#echo-cancellation-g168} +ITU-T Recommendation G.168, which specifies digital network echo cancellers. It covers their performance, how tones disable them for fax and data, and the laboratory tests to check them. + +See also: [Echo cancellation](#echo-cancellation). + +### EDB +**Emergency Database.** In UK telephony, the database that tells emergency services the address behind the number calling 999. + +### EDGE +**Enhanced Data rates for GSM Evolution.** An upgrade to GSM data, also called EGPRS, that uses better modulation and coding to roughly triple GPRS speeds on the same radio channels. + +See also: [GPRS](g-k.md#gprs), [GSM](g-k.md#gsm), [GERAN](g-k.md#geran). + +### Editor +In an inspection, the person who makes the fixes to the artefact afterwards, usually its author. + +See also: [Inspection](g-k.md#inspection). + +### EFM +**Ethernet in the First Mile.** IEEE 802.3ah, which defines Ethernet over the access link between provider and customer, on copper or fibre, with its own management functions. + +See also: [Ethernet over twisted pair](#ethernet-over-twisted-pair), [EoFTTC](#eofttc). + +### Egress +Traffic leaving a network or a device, as opposed to ingress traffic coming in. + +See also: [Ingress](g-k.md#ingress). + +### EIA +**Electronic Industries Alliance.** A former US standards and trade body for electronics manufacturers, known for standards such as RS-232. It closed in 2011 and its work passed to other bodies, including the TIA. + +See also: [TIA](s-z.md#tia). + +### EIGRP +**Enhanced Interior Gateway Routing Protocol.** Cisco's advanced distance-vector routing protocol, which sends only incremental updates. It replaced IGRP in 1993 and was published as RFC 7868 in 2016. + +See also: [IGRP](g-k.md#igrp), [OSPF](o-r.md#ospf), [IGP](g-k.md#igp). + +### Embedded systems programming +Writing software for an embedded system, a computer built into a device, using the interfaces and limited resources the device provides. + +See also: [RTOS](o-r.md#rtos), [MCU](l-n.md#mcu), [C Language](a-c.md#c-language). + +### Engineering Discussion +A meeting to frame a problem and look for solutions. If materials go out beforehand for people to read, it is closer to a preview. + +See also: [Preview](o-r.md#preview). + +### Engineering Management +**EM.** Planning, staffing, tracking and controlling software projects, together with managing the teams and the organisation. + +### Engineering Process +Software engineering process: defining how software engineering work is done, and improving it. + +See also: [Process](o-r.md#process). + +### EoFTTC +**Ethernet over FTTC.** A business Ethernet service over fibre to the cabinet: copper runs from the premises to the street cabinet, and fibre from there to the exchange. It gives symmetrical speeds of tens of megabits per second at lower cost than a fibre leased line. + +See also: [EAD](#ead), [VDSL](s-z.md#vdsl), [EFM](#efm). + +### EoS +**Ethernet over SDH or SONET.** Protocols that carry Ethernet over SDH or SONET networks. They usually use the generic framing procedure (GFP) and virtual concatenation to fit the Ethernet rate into SDH paths. + +See also: [SDH](s-z.md#sdh), [SONET](s-z.md#sonet). + +### ePDG +**Evolved Packet Data Gateway.** The LTE core node that lets devices on untrusted non-3GPP access, such as public Wi-Fi, reach the mobile core through an IPsec tunnel. Wi-Fi calling relies on it. + +See also: [PGW](o-r.md#pgw), [IPSec](g-k.md#ipsec), [ANDSF](a-c.md#andsf). + +### Epic +A large user story, too big for one iteration, that is split into smaller stories. + +See also: [User Stories](s-z.md#user-stories), [Story Splitting](s-z.md#story-splitting). + +### EPWS +**Ethernet Private Wire Service.** A point-to-point Ethernet service between two customer sites, carried over the provider's network. + +See also: [EVPL](#evpl), [VPWS](s-z.md#vpws). + +### ESB +**Enterprise Service Bus.** Middleware in a service-oriented architecture that connects applications through a shared bus. It routes, transforms and mediates messages between them, so that each application integrates with the bus rather than with every other application. + +See also: [SOA](s-z.md#soa), [Microservice](l-n.md#microservice). + +### Estimate +The result of estimating: the predicted size, effort, cost or duration, with the inputs, assumptions and method behind it. It can be a full project estimate or a one-line task estimate. + +See also: [Estimation](#estimation), [Project Estimate](o-r.md#project-estimate), [Task Estimate](s-z.md#task-estimate). + +### Estimation +Working out the likely size, effort, cost, schedule or quality of a project. Several techniques used together give a better estimate than one, and estimates should be redone as the project goes on. + +See also: [Estimate](#estimate), [Cone of Uncertainty](a-c.md#cone-of-uncertainty), [Planning Poker](o-r.md#planning-poker). + +### Ethernet over twisted pair +Ethernet physical layers that use twisted-pair copper cable. 10BASE-T, 100BASE-TX, 1000BASE-T and 10GBASE-T are the main ones. Single-pair variants, such as 10BASE-T1L, serve industrial and automotive uses. + +See also: [Cat 5](a-c.md#cat-5), [Cat 6](a-c.md#cat-6), [Twisted pair](s-z.md#twisted-pair). + +### Ethical Hacking +Testing an organisation's security with its permission, using attackers' methods to find weaknesses before they do. Ethical hackers are also called white hats. + +See also: [Pen testing](o-r.md#pen-testing). + +### ETL +**Extract, Transform, Load.** The three steps for moving data into a data warehouse: read data from source systems, convert and clean it into the target form, and write it into the target. + +See also: [Data Warehouse](#data-warehouse). + +### ETSI +**European Telecommunications Standards Institute.** The not-for-profit body, based in Sophia Antipolis in France, that sets European telecoms standards. Its work includes GSM, DECT and TETRA, and it is a founding partner of 3GPP. + +See also: [ITU](g-k.md#itu), [GSM](g-k.md#gsm). + +### EVC +**Ethernet Virtual Connection.** In Metro Ethernet Forum (MEF) terms, the association between two or more customer interfaces (UNIs) across a provider's network. It is a virtual pipe that defines which sites can exchange frames. + +See also: [EVPL](#evpl), [UNI](s-z.md#uni). + +### Evolutionary Delivery Lifecycle +A lifecycle that combines evolutionary prototyping with staged delivery. + +See also: [Evolutionary Prototyping Lifecycle](#evolutionary-prototyping-lifecycle), [Staged Delivery Lifecycle](s-z.md#staged-delivery-lifecycle). + +### Evolutionary Prototyping Lifecycle +A lifecycle in which a system grows from an initial concept through repeated prototypes until it is ready to deliver. + +See also: [Lifecycle](l-n.md#lifecycle), [Iterative Development](g-k.md#iterative-development). + +### EVPL +**Ethernet Virtual Private Line.** An MEF E-Line service that carries several point-to-point virtual connections over one customer interface, separated by VLAN. Its sibling, Ethernet Private Line (EPL), gives one transparent connection per port. + +See also: [EVC](#evc), [EPWS](#epws). + +### Expert Judgement +Estimating from the experience of people who know the work. It works best when combined with other techniques, such as analogy and decomposition. + +See also: [Estimation](#estimation), [Analogy Estimation](a-c.md#analogy-estimation). + +### Explicit Change Control +Change control of artefacts, such as requirements and plans, that a change control board manages directly. + +See also: [Implicit Change Control](g-k.md#implicit-change-control), [Change Control Board](a-c.md#change-control-board). + +### Explicit Risk Management +See [Extrinsic Risk Management](#extrinsic-risk-management). + +### Exploratory Testing +Testing in which the tester learns about the software, designs tests and runs them all at once, rather than following a script. + +See also: [Informal Testing](g-k.md#informal-testing). + +### Extrinsic Risk Management +Formal risk management added to a project, such as keeping a top-ten risk list and reviewing it regularly. + +See also: [Intrinsic Risk Management](g-k.md#intrinsic-risk-management), [Risk Management](o-r.md#risk-management). + +## F + +### Facilitation +Running a meeting or workshop so the group reaches its goal, without taking part in the content. The person who does it is the facilitator. + +### FCS +**Frame Check Sequence.** An error-detecting code, usually a CRC, added to the end of a frame. A receiver that finds a mismatch discards the frame; protocols higher up, such as TCP, recover the loss. + +See also: [CRC](a-c.md#crc). + +### FDDI +**Fibre Distributed Data Interface.** A 100 Mbit/s token-passing LAN standard over a dual fibre ring. Fast Ethernet made it obsolete. + +See also: [Token Ring](s-z.md#token-ring), [100 Mbps (Fast Ethernet)](s-z.md#100-mbps-fast-ethernet). + +### Feature +A piece of a system's functionality, seen from the user's side. The term also refers to a project's scope, measured in features. + +See also: [Feature Test](#feature-test), [Feature creep](#feature-creep). + +### Feature creep +The tendency for requirements to keep growing during a project, adding features that were never planned, at a cost to schedule and quality. + +See also: [Change Control](a-c.md#change-control). + +### Feature Test +A test of one area of system functionality once its construction is finished. + +### FemtoCell +A small, low-power mobile base station for a home or small office, connected to the operator over the customer's broadband. It improves indoor coverage for a handful of phones. + +See also: [Mobile Cell](l-n.md#mobile-cell), [E NodeB](#e-nodeb). + +### FIPS +**Federal Information Processing Standards.** US federal government standards for computer systems, issued by NIST, covering areas such as cryptography where no suitable industry standard exists. + +See also: [FIPS 140-2](#fips-140-2), [NIST](l-n.md#nist). + +### FIPS 140-2 +The US standard, from 2001, of security requirements for cryptographic modules. It defines four security levels and covers module design, ports, roles, physical security and key management. FIPS 140-3 replaced it in 2019, and 140-2 certificates are being retired. + +See also: [FIPS](#fips), [NIST](l-n.md#nist). + +### Firewall +A network security device or software that allows or blocks traffic by rules, usually between a trusted internal network and an untrusted one. Network firewalls protect whole networks; host-based firewalls protect one machine. + +See also: [DMZ](#dmz), [IPS](g-k.md#ips), [DPI](#dpi). + +### FNA +**Full Network Authentication.** A broadband login method in which the network authenticates the line itself, by its network identifier, through RADIUS, rather than a username and password typed by the customer. + +See also: [Radius](o-r.md#radius), [PPPoE](o-r.md#pppoe). + +### Formal Testing +Testing that follows documented test cases. + +See also: [Informal Testing](g-k.md#informal-testing), [Test Case](s-z.md#test-case). + +### Fortran +The first widely used high-level language, developed at IBM in the 1950s for scientific computing. Modern Fortran is still used for numerical work and supercomputing. + +See also: [COBOL](a-c.md#cobol). + +### Forwarding plane +See [Data Plane](#data-plane). + +### FOTA +**Firmware Over-The-Air.** Updating device firmware remotely over a wireless link. A safe design verifies a signature on each image and keeps two partitions, so a failed update rolls back. It also rolls updates out to the fleet in stages. + +See also: [Root of Trust](o-r.md#root-of-trust), [LwM2M](l-n.md#lwm2m). + +### FQDN +**Fully Qualified Domain Name.** A domain name that names every level of the DNS hierarchy down from the root, such as `www.example.com.`, so it can mean only one thing. + +See also: [Domain Name](#domain-name), [DNS](#dns). + +### Frame Relay +A packet-switched WAN technology, widely sold by carriers in the 1990s, that connects sites through virtual circuits over a shared network. It was cheaper than leased lines; MPLS VPNs have since replaced it. + +See also: [X.25](s-z.md#x25), [PVC](o-r.md#pvc), [L3VPN](l-n.md#l3vpn). + +### Frequent Releases +Putting the product into users' hands often, so the team gets feedback early and acts on it. + +See also: [Continuous Deployment](a-c.md#continuous-deployment), [Release](o-r.md#release). + +### Frequently Asked Question +**FAQ.** A list of common questions and their answers. + +### FSK +**Frequency-Shift Keying.** Modulation that sends digital data by switching the carrier between frequencies; in binary FSK, one frequency for 1 and another for 0. Caller ID and early modems use it. + +See also: [QAM](o-r.md#qam). + +### FTP +**File Transfer Protocol.** A protocol for transferring files between a client and a server, using separate control and data connections. It sends credentials in clear text, so FTPS or SFTP should be used instead. + +See also: [FTPS](#ftps), [SFTP](s-z.md#sftp). + +### FTPS +**FTP Secure.** FTP with TLS encryption added. It is a different protocol from SFTP, which runs over SSH. + +See also: [FTP](#ftp), [SFTP](s-z.md#sftp), [TLS](s-z.md#tls). + +### Full duplex +Communication in which both ends can send and receive at the same time, like a telephone call. + +See also: [Duplex](#duplex), [Half Duplex](g-k.md#half-duplex). + +### Function Point +A measure of software size based on the functionality it gives users, counted from its inputs, outputs, enquiries, files and interfaces. + +See also: [Lines of Code](l-n.md#lines-of-code), [Estimation](#estimation). + +### Functional Requirement +Something a system must do to meet the business requirements. Also called a [What Requirement](s-z.md#what-requirement). + +See also: [Non-functional Requirement](l-n.md#non-functional-requirement), [Business Requirement](a-c.md#business-requirement). + +### Functional Testing +Testing a system's behaviour against what is expected, without regard to how it works inside. Also called black-box testing. + +See also: [Black-Box Testing](a-c.md#black-box-testing). + +### Fuzzy Front End +The early, ill-defined stage of a project, from the first idea to the approval of the project charter. + +See also: [Project Charter](o-r.md#project-charter). + +### Fuzzy Logic +In estimation, sorting items into rough size bands, such as small, medium and large, each standing for an overlapping range of values. In computing generally, fuzzy logic means reasoning with degrees of truth between 0 and 1. + +See also: [T-Shirt Sizing](s-z.md#t-shirt-sizing), [Analogy Estimation](a-c.md#analogy-estimation). + +### FXO +**Foreign Exchange Office.** The port on a device, such as a phone, fax or VoIP gateway, that plugs into an analogue telephone line and receives dial tone and ringing from it. + +See also: [FXS](#fxs). + +### FXS +**Foreign Exchange Station.** The port that provides an analogue telephone line: it supplies power, dial tone and ringing to the phone connected to it. An exchange line or an analogue adapter has FXS ports. + +See also: [FXO](#fxo). diff --git a/content/glossary/g-k.md b/content/glossary/g-k.md new file mode 100644 index 0000000..ce0dea5 --- /dev/null +++ b/content/glossary/g-k.md @@ -0,0 +1,711 @@ +--- +title: Glossary, G to K +--- + +# G to K + +## G + +### G.711 {#g711} +The ITU-T standard, from 1972, for coding telephone speech as 64 kbit/s PCM: 8,000 samples a second, each companded to 8 bits. It has two variants, A-law and µ-law. It is the baseline codec that every VoIP system supports. + +See also: [A-law](a-c.md#a-law), [Mu-law](l-n.md#mu-law), [PCM](o-r.md#pcm), [G.711.1](#g7111). + +### G.711.1 {#g7111} +A wideband extension of G.711, from 2008, that adds layers on top of a G.711 core. It runs at 64, 80 or 96 kbit/s, and a G.711-only receiver can still decode the core. + +See also: [G.711](#g711), [G.722](#g722). + +### G.719 {#g719} +An ITU-T codec for full-band audio (20 Hz to 20 kHz) at 32 to 128 kbit/s, developed by Polycom and Ericsson for high-quality conferencing. It handles music as well as speech. + +See also: [G.722](#g722), [Audio Codecs](a-c.md#audio-codecs). + +### G.722 {#g722} +An ITU-T wideband speech codec from 1988, covering 50 to 7,000 Hz at 48 to 64 kbit/s using sub-band ADPCM. It is widely used for HD voice on desk phones. G.722.1 and G.722.2 (AMR-WB) are different codecs despite the names. + +See also: [G.711](#g711), [AMR-WB](a-c.md#amr-wb). + +### G.723.1 {#g7231} +An ITU-T low-rate speech codec, at 5.3 or 6.3 kbit/s, with 30 ms frames. It was common in early VoIP and H.323 systems. It is unrelated to the older G.723. + +See also: [G.726](#g726), [H.323](#h323). + +### G.726 {#g726} +An ITU-T ADPCM speech codec at 16, 24, 32 or 40 kbit/s, which replaced G.721 and G.723. The 32 kbit/s rate, half that of G.711, is the most used, for example in DECT cordless phones. + +See also: [G.711](#g711), [PCM](o-r.md#pcm). + +### G.Fast {#gfast} +An ITU-T DSL standard (G.9700 and G.9701) for very short copper lines, up to a few hundred metres, giving several hundred megabits per second. It is used from a distribution point or cabinet fed by fibre. + +See also: [VDSL](s-z.md#vdsl), [DSL](d-f.md#dsl), [DP](d-f.md#dp). + +### Gantt chart +A bar chart of a project schedule, with tasks down the side and time along the top. It shows when each task starts and ends, and how the tasks depend on each other. + +See also: [PERT chart](o-r.md#pert-chart), [CPM](a-c.md#cpm). + +### Gap analysis +Comparing where things are now with where they need to be, to find what must change to get there. + +### Gate +A set of criteria that must be met before work can pass from one phase or stage to the next. + +See also: [Gate Checklist](#gate-checklist), [Phase](o-r.md#phase). + +### Gate Checklist +A checklist used to check that the criteria for a gate have been met. + +See also: [Gate](#gate). + +### GBE / GE {#gbe-ge} +Abbreviations for [Gigabit Ethernet](#gigabit-ethernet). + +### GCHQ +**Government Communications Headquarters.** The UK's signals intelligence and security agency, based in Cheltenham. It grew out of the Government Code and Cypher School of Bletchley Park, and runs the National Cyber Security Centre. + +See also: [NCSC](l-n.md#ncsc), [CESG](a-c.md#cesg). + +### Geocast +Delivering a message to all the nodes in a geographical area, rather than to a list of addresses. It is a form of multicast used in some mobile ad hoc and vehicle networks. + +See also: [Multicast](l-n.md#multicast), [MANET](l-n.md#manet). + +### GERAN +**GSM EDGE Radio Access Network.** The radio access network of GSM and EDGE: the base stations, their controllers and the interfaces between them. 3GPP maintains its standards. + +See also: [BTS](a-c.md#bts), [BSC](a-c.md#bsc), [EDGE](d-f.md#edge), [UTRAN](s-z.md#utran). + +### GGSN +**Gateway GPRS Support Node.** The GPRS and UMTS core node that connects the mobile packet network to external networks such as the internet. It allocates the device's IP address and anchors the session as the user moves. In LTE the PGW does this job. + +See also: [SGSN](s-z.md#sgsn), [GPRS](#gprs), [APN](a-c.md#apn), [PGW](o-r.md#pgw). + +### Gherkin +The plain-language format used by Cucumber and similar tools to write behaviour-driven tests. Scenarios are written as `Given`, `When` and `Then` steps under a `Feature`, so that business people and developers can read the same tests. + +See also: [BDD](a-c.md#bdd), [Given When Then](#given-when-then). + +### Gigabit Ethernet +Ethernet at 1 Gbit/s, defined in IEEE 802.3. It replaced Fast Ethernet as the usual speed for wired networks from the early 2000s. + +See also: [GBE / GE](#gbe-ge), [100 Mbps (Fast Ethernet)](s-z.md#100-mbps-fast-ethernet), [Ethernet over twisted pair](d-f.md#ethernet-over-twisted-pair). + +### Git +A distributed version control system, created by Linus Torvalds in 2005 for the Linux kernel. Every clone holds the full history, so most work is local and fast, and branching and merging are cheap. + +See also: [Version Control](s-z.md#version-control), [Subversion](s-z.md#subversion). + +### Given When Then +A template for writing acceptance criteria and tests: given some context, when an action happens, then expect these results. + +See also: [Gherkin](#gherkin), [BDD](a-c.md#bdd). + +### GMSC +**Gateway Mobile Switching Centre.** An MSC function that routes calls between the mobile network and other networks. For an incoming call it asks the HLR where the subscriber is. + +See also: [MSC](l-n.md#msc), [HLR](#hlr). + +### GNU +**GNU's Not Unix.** The free software operating system started by Richard Stallman in 1983, made up of tools, libraries and compilers. Combined with the Linux kernel, it forms most Linux distributions. + +See also: [GPL](#gpl), [Linux](l-n.md#linux), [Copyleft](a-c.md#copyleft). + +### Go +A statically typed, compiled language created at Google in 2009 by Robert Griesemer, Rob Pike and Ken Thompson. It has garbage collection, built-in concurrency with goroutines and channels, and fast builds. It is also called Golang. + +### Goals +The results a project, process or activity is meant to achieve. Also called objectives. + +See also: [Objectives](o-r.md#objectives). + +### GoF +**Gang of Four.** The four authors (Gamma, Helm, Johnson and Vlissides) of *Design Patterns: Elements of Reusable Object-Oriented Software* (1994). The book catalogues 23 object-oriented design patterns. + +See also: [Design Pattern](d-f.md#design-pattern). + +### Google Cloud Platform +Google's cloud computing services, offering infrastructure, platform and serverless computing, data analytics and machine learning on the infrastructure Google uses itself. + +See also: [AWS](a-c.md#aws), [Azure](a-c.md#azure). + +### GPL + +**GNU General Public License.** + +The most widely used copyleft free software licence, written by Richard Stallman. It lets anyone run, study, share and change the software, as long as they share copies and derived works under the same licence. + +See also: [Copyleft](a-c.md#copyleft), [GNU](#gnu). + +### GPRS +**General Packet Radio Service.** The packet data service added to GSM, giving always-on connections charged by data volume rather than by time. It is best-effort, with speeds of tens of kilobits per second. + +See also: [GSM](#gsm), [EDGE](d-f.md#edge), [SGSN](s-z.md#sgsn), [GGSN](#ggsn). + +### GSM +**Global System for Mobile communications.** The second-generation (2G) digital mobile standard, developed by ETSI and first launched in 1991. It was designed for circuit-switched voice and SMS, and GPRS and EDGE later added data. + +See also: [GPRS](#gprs), [EDGE](d-f.md#edge), [UMTS](s-z.md#umts), [SIM](s-z.md#sim). + +### GSM AMR +The AMR speech codec as used in GSM. See [AMR-NB](a-c.md#amr-nb). + +### GSM-FR +**GSM Full Rate.** The first GSM speech codec (GSM 06.10), at 13 kbit/s. Its quality is poor by modern standards; Enhanced Full Rate and AMR replaced it. + +See also: [GSM AMR](#gsm-amr), [AMR-NB](a-c.md#amr-nb). + +### GSM-R +**GSM for Railways.** A version of GSM for railway voice and data, including the signalling of the European Rail Traffic Management System. It is designed to work at train speeds up to 500 km/h. + +See also: [GSM](#gsm). + +### GSN +**GPRS Support Node.** A node in the GPRS core network: either a serving node (SGSN) or a gateway node (GGSN). + +See also: [SGSN](s-z.md#sgsn), [GGSN](#ggsn). + +## H + +### H.248 {#h248} +**Gateway Control Protocol (Megaco).** The ITU-T and IETF protocol with which a media gateway controller or softswitch controls media gateways, which convert between telephone circuits and IP media streams. It does the same job as MGCP. + +See also: [MGCP](l-n.md#mgcp), [MGW](l-n.md#mgw), [Softswitch](s-z.md#softswitch). + +### H.323 {#h323} +An ITU-T family of protocols for voice and video calls over packet networks, covering signalling, media and bandwidth control. It was the main VoIP standard before SIP replaced it. + +See also: [SIP](s-z.md#sip), [Q.931](o-r.md#q931), [RAS](o-r.md#ras). + +### Half Duplex +Communication in which both ends can send, but only one at a time, like a push-to-talk radio. + +See also: [Duplex](d-f.md#duplex), [Full duplex](d-f.md#full-duplex), [Simplex](s-z.md#simplex). + +### Happy Path +See [Nominal Path](l-n.md#nominal-path). + +### Hash Function +A function that maps data of any size to a fixed-size value. A cryptographic hash, such as SHA-256, is also one-way and collision-resistant. That makes it useful for integrity checks, digital signatures and storing passwords. + +See also: [SHA](s-z.md#sha), [MD5](l-n.md#md5), [CRC](a-c.md#crc). + +### HDF +**Handover Distribution Frame.** In UK local loop unbundling, the frame in the exchange where the copper pairs are handed over from the main distribution frame to another operator's equipment. + +See also: [MDF](l-n.md#mdf), [Local Loop](l-n.md#local-loop). + +### HDLC +**High-Level Data Link Control.** An ISO bit-oriented, synchronous data link protocol. Many other link protocols, including PPP framing, LAPB in X.25 and LAPD in ISDN, are based on it. + +See also: [PPP](o-r.md#ppp), [X.25](s-z.md#x25), [Frame Relay](d-f.md#frame-relay). + +### HDSL +**High-bit-rate Digital Subscriber Line.** A symmetrical DSL that carries a 2 Mbit/s (E1) or 1.5 Mbit/s (T1) circuit over two or three copper pairs. It was used to deliver leased lines without new cable. + +See also: [SDSL](s-z.md#sdsl), [DSL](d-f.md#dsl). + +### Heartbeat Retrospective +A retrospective held at a regular interval, such as the end of each iteration, in which the team reflects on recent events and agrees improvements. + +See also: [Sprint retrospective](s-z.md#sprint-retrospective). + +### HiFi Prototype +See [High Fidelity Prototype](#high-fidelity-prototype). + +### High Fidelity Prototype +A prototype that looks and behaves much like the finished system, usually built with real development tools. + +See also: [Low Fidelity Prototype](l-n.md#low-fidelity-prototype), [User Interface Prototype](s-z.md#user-interface-prototype). + +### High Level Design +**HLD.** The design level between the architecture and the low-level design. It defines the components of the solution, their interfaces and how they interact, without going into how each is built. + +See also: [Low Level Design](l-n.md#low-level-design), [Architecture](a-c.md#architecture). + +### HLD +See [High Level Design](#high-level-design). + +### HLR +**Home Location Register.** The central database of a GSM or UMTS network, holding each subscriber's details: their IMSI, phone numbers, services and current location. In LTE and IMS, the HSS replaced it. + +See also: [VLR](s-z.md#vlr), [HSS](#hss), [IMSI](#imsi), [MSC](l-n.md#msc). + +### Hotfix +A small, urgent change, sometimes called a patch, that fixes a bug in released software outside the normal release cycle. + +See also: [Release](o-r.md#release). + +### How Requirement +Usually a synonym for [Non-functional Requirement](l-n.md#non-functional-requirement); sometimes used for design constraints. + +### How Well Requirement +See [Non-functional Requirement](l-n.md#non-functional-requirement). + +### HSRP +**Hot Standby Router Protocol.** Cisco's protocol for a fault-tolerant default gateway. Two or more routers share a virtual IP address; one is active and the others take over if it fails. VRRP is the open-standard equivalent. + +See also: [Router](o-r.md#router). + +### HSS +**Home Subscriber Server.** The master subscriber database for IMS and LTE, holding user profiles and authentication data and tracking where users are registered. It takes over the jobs of the HLR and the authentication centre. + +See also: [HLR](#hlr), [IMS](#ims), [CSCF](a-c.md#cscf), [MME](l-n.md#mme). + +### HTTP +**Hypertext Transfer Protocol.** The request-response protocol of the web. A client asks for a resource by URL with a method such as `GET` or `POST`, and the server returns a status and content. HTTP/2 and HTTP/3 keep the same model with more efficient transports. + +See also: [HTTPS](#https), [REST](o-r.md#rest), [URL](s-z.md#url). + +### HTTPS +HTTP over TLS. It encrypts the traffic and lets the client check the server's identity through its certificate, protecting against eavesdropping and tampering. + +See also: [HTTP](#http), [TLS](s-z.md#tls), [CA](a-c.md#ca). + +### Hub +A network device that repeats every frame it receives to all its other ports, so all connected devices share one collision domain. It works at layer 1, and switches have replaced it. + +See also: [Switch](s-z.md#switch), [L1](l-n.md#l1). + +### Human factors +The study of how people behave, physically and mentally, with products, systems and environments, and how to design for them. + +See also: [User Experience](s-z.md#user-experience). + +### Hungarian notation +A naming convention in which a prefix on an identifier shows its kind or type, such as `cApples` for a count or `szName` for a zero-terminated string. Most modern style guides advise against encoding the type in this way. + +See also: [Camel Case](a-c.md#camel-case), [Snake Case](s-z.md#snake-case). + +## I + +### IA +**Information Assurance.** Managing the risks to information and the systems that handle it, so that it keeps its confidentiality, integrity, availability, authenticity and non-repudiation. + +See also: [CESG](a-c.md#cesg), [NCSC](l-n.md#ncsc). + +### IaaS +**Infrastructure as a Service.** Cloud computing that rents virtual machines, storage and networks, which the customer manages from the operating system up. + +See also: [PaaS](o-r.md#paas), [SaaS](s-z.md#saas), [NaaS](l-n.md#naas). + +### ICE +**Interactive Connectivity Establishment.** A technique, defined in RFC 8445, for finding the most direct working path between two peers behind NATs and firewalls. It tries candidate addresses gathered with STUN and TURN. SIP and WebRTC media use it. + +See also: [STUN](s-z.md#stun), [NAT](l-n.md#nat). + +### ICMP +**Internet Control Message Protocol.** The IP protocol that carries error and diagnostic messages, such as "destination unreachable" and the echo request and reply used by `ping`. + +See also: [ICMPv6](#icmpv6), [Internet Protocol Suite](#internet-protocol-suite). + +### ICMPv6 +ICMP for IPv6, defined in RFC 4443. As well as errors and `ping`, it carries Neighbour Discovery, which replaces ARP, and Multicast Listener Discovery, which replaces IGMP. + +See also: [ICMP](#icmp), [IPv6](#ipv6). + +### IDE +**Integrated Development Environment.** An application that combines a code editor, build tools and a debugger, and often much more, for writing software. + +See also: [Integrated Development Environment](#integrated-development-environment). + +### IDQ +**Informatica Data Quality.** Informatica's tool for profiling, cleansing and standardising enterprise data. + +See also: [DQ](d-f.md#dq). + +### IEC +**International Electrotechnical Commission.** The international body that publishes standards for electrical and electronic technologies. It works with ISO on information technology standards, such as the ISO/IEC series. + +See also: [ISO](#iso). + +### IEEE +**Institute of Electrical and Electronics Engineers.** The world's largest professional association of engineers. It publishes many standards, including the 802 family for LANs: Ethernet (802.3) and Wi-Fi (802.11). + +See also: [802.11](s-z.md#80211), [802.3 Physical Layer](s-z.md#8023-physical-layer). + +### IEEE 802.1ah {#ieee-8021ah} +**Provider Backbone Bridges (PBB), or MAC-in-MAC.** An IEEE standard that wraps customer Ethernet frames in a provider's own Ethernet header. Providers can then scale carrier Ethernet without learning customer MAC addresses or running out of VLAN IDs. + +See also: [IEEE 802.1Qay](#ieee-8021qay), [VLAN](s-z.md#vlan). + +### IEEE 802.1Qay {#ieee-8021qay} +**Provider Backbone Bridge Traffic Engineering (PBB-TE).** A carrier Ethernet standard that builds on 802.1ah MAC-in-MAC. It removes flooding and spanning tree and has the operator set up paths explicitly, giving predictable, SDH-like behaviour. + +See also: [IEEE 802.1ah](#ieee-8021ah), [SDH](s-z.md#sdh). + +### IETF +**Internet Engineering Task Force.** The open standards body that develops internet protocols, such as TCP/IP, HTTP and TLS, and publishes them as RFCs. + +See also: [RFC](o-r.md#rfc). + +### IGMP +**Internet Group Management Protocol.** The IPv4 protocol with which hosts tell their local routers which multicast groups they want to receive. IPTV uses it to join channels. + +See also: [Multicast](l-n.md#multicast), [IPTV](#iptv). + +### IGP +**Interior Gateway Protocol.** A routing protocol used within one autonomous system, such as OSPF, IS-IS, RIP or EIGRP. + +See also: [BGP](a-c.md#bgp), [OSPF](o-r.md#ospf), [RIP](o-r.md#rip). + +### IGRP +**Interior Gateway Routing Protocol.** Cisco's original distance-vector routing protocol, which used a composite metric of bandwidth and delay. EIGRP replaced it. + +See also: [EIGRP](d-f.md#eigrp), [RIP](o-r.md#rip). + +### IIS +**Internet Information Services.** Microsoft's web server for Windows Server. + +### IKE +**Internet Key Exchange.** The protocol that sets up security associations for IPsec. The peers authenticate each other and agree keys using Diffie-Hellman. IKEv2 is the current version. + +See also: [IPSec](#ipsec), [VPN](s-z.md#vpn). + +### iLBC +**Internet Low Bitrate Codec.** A royalty-free narrowband speech codec at about 13 to 15 kbit/s, designed to cope well with packet loss. It was part of WebRTC. + +See also: [OPUS](o-r.md#opus), [Audio Codecs](a-c.md#audio-codecs). + +### iManager +Huawei's network management software for its access equipment, such as MSANs and DSLAMs. + +### IMAP +**Internet Message Access Protocol.** The protocol email clients use to read and manage mail held on a server, so that several devices see the same mailbox. It uses port 143, or 993 over TLS. + +See also: [POP](o-r.md#pop). + +### Implementation +A synonym for construction, deployment or both, depending on context. + +See also: [Construction](a-c.md#construction), [Deployment](d-f.md#deployment). + +### Implementation Lead +A synonym for the construction lead, the deployment lead or both. + +### Implicit Change Control +Control of artefacts, such as source code, that the change control board does not manage directly, but which change only when the controlled artefacts they derive from change. + +See also: [Explicit Change Control](d-f.md#explicit-change-control). + +### Implicit Risk Management +See [Intrinsic Risk Management](#intrinsic-risk-management). + +### IMS +**IP Multimedia Subsystem.** The 3GPP architecture for delivering voice, video and messaging over IP using SIP. It is the core behind VoLTE, Wi-Fi calling and many fixed-line VoIP networks. + +See also: [CSCF](a-c.md#cscf), [HSS](#hss), [SIP](s-z.md#sip), [VoLTE](s-z.md#volte). + +### IMSI +**International Mobile Subscriber Identity.** The unique number, of up to 15 digits, that identifies a mobile subscriber, stored on the SIM. It is made up of the mobile country code, the network code and the subscriber number. Networks send it as rarely as possible, using temporary identities instead, to stop tracking. + +See also: [SIM](s-z.md#sim), [HLR](#hlr), [MNC](l-n.md#mnc). + +### IN +**Intelligent Network.** The ITU-T architecture (Q.1200 series) that moves service logic out of telephone switches into separate service control points. Freephone, number translation and prepaid services were built on it. + +See also: [INAP](#inap), [CAMEL](a-c.md#camel), [SS7](s-z.md#ss7). + +### INAP +**Intelligent Network Application Part.** The SS7 protocol, over TCAP, between switches and service control points in an Intelligent Network. + +See also: [IN](#in), [TCAP](s-z.md#tcap), [CAP](a-c.md#cap). + +### Inch-Pebble +See [Miniature Milestone](l-n.md#miniature-milestone). + +### Incremental Development +Building a product in increments, where each version is usable and adds user-visible functionality to the one before. + +See also: [Iterative Development](#iterative-development). + +### Informal Review +Any review other than an inspection, such as a walkthrough or desk check. + +See also: [Inspection](#inspection), [Walkthrough](s-z.md#walkthrough), [Desk Check](d-f.md#desk-check). + +### Informal Testing +Testing based on the tester's judgement, without documented test cases. + +See also: [Formal Testing](d-f.md#formal-testing), [Exploratory Testing](d-f.md#exploratory-testing). + +### Information architecture +How information in a system or site is organised, structured and labelled so that people can find and understand it. + +See also: [Information design](#information-design). + +### Information design +Planning the specific information to give a particular audience, and how to present it, to meet given goals. + +See also: [Information architecture](#information-architecture). + +### Information Radiators +Large, visible displays, such as task boards or burndown charts, placed where the whole team can see the current state of work at a glance. + +See also: [Task Board](s-z.md#task-board), [Kanban Board](#kanban-board), [Burndown Chart](a-c.md#burndown-chart). + +### Ingress +Traffic entering a network or a device, as opposed to egress traffic leaving it. + +See also: [Egress](d-f.md#egress). + +### Inspection +A formal review with defined roles (moderator, author, reader, inspectors and scribe), preparation, a logging meeting, rework and follow-up. + +See also: [Moderator](l-n.md#moderator), [Inspector](#inspector), [Reading Inspection](o-r.md#reading-inspection). + +### Inspector +A reviewer in an inspection. + +See also: [Inspection](#inspection). + +### Institute of Electrical and Electronics Engineers +See [IEEE](#ieee). + +### Integrated Development Environment +See [IDE](#ide). + +### Integration +Combining software components and making them work together. + +See also: [Integration Test](#integration-test), [Continuous Integration](a-c.md#continuous-integration). + +### Integration Test +A test that checks that components work together correctly after they are combined or changed. + +See also: [Unit Testing](s-z.md#unit-testing), [System Test](s-z.md#system-test). + +### Internet Protocol Suite +The protocols of the internet, often called TCP/IP after its two main protocols. It has four layers: link, internet (IP), transport (TCP, UDP) and application (such as HTTP or DNS). + +See also: [TCP](s-z.md#tcp), [UDP](s-z.md#udp), [IPv4](#ipv4), [IPv6](#ipv6). + +### Interpreted Language +A language whose usual implementations run the source, or bytecode compiled from it, through an interpreter rather than compiling it ahead of time to machine code. Python and JavaScript are examples. The distinction is about implementations rather than languages. + +See also: [Compiled Language](a-c.md#compiled-language). + +### Intrinsic Risk Management +Managing risk through how a project is run, for example by choosing a lifecycle and practices that expose and reduce risks as a matter of course. + +See also: [Extrinsic Risk Management](d-f.md#extrinsic-risk-management). + +### INVEST +A checklist for good user stories: Independent, Negotiable, Valuable, Estimable, Small and Testable. + +See also: [User Stories](s-z.md#user-stories), [Definition of Ready](d-f.md#definition-of-ready). + +### IOS +**Internetwork Operating System.** The operating system on most Cisco routers and switches, known for its command-line interface. + +### IPS +**Intrusion Prevention System.** A device or software that watches network or host activity for attacks and policy breaches and blocks them. An intrusion detection system (IDS) only reports them. + +See also: [Firewall](d-f.md#firewall), [DPI](d-f.md#dpi). + +### IPSC +**IP Stream Connect.** A BT Wholesale product that handed over broadband customers' traffic to an internet service provider at a central point. + +See also: [ISP](#isp), [L2TP](l-n.md#l2tp). + +### IPSec +**Internet Protocol Security.** A suite of protocols that authenticate and encrypt IP packets, between hosts, between gateways or between a host and a gateway. It is widely used for VPNs; IKE sets up its keys. + +See also: [IKE](#ike), [VPN](s-z.md#vpn), [ePDG](d-f.md#epdg). + +### IPTV +**Internet Protocol Television.** Television delivered over a managed IP network, usually by multicast to a set-top box, rather than by broadcast or the open internet. + +See also: [IGMP](#igmp), [STB](s-z.md#stb), [VOD](s-z.md#vod). + +### IPv4 +**Internet Protocol version 4.** The original version of IP, from 1981 (RFC 791), with 32-bit addresses. It still carries much of the internet's traffic, stretched by NAT because its address space is too small. + +See also: [IPv6](#ipv6), [NAT](l-n.md#nat). + +### IPv6 +**Internet Protocol version 6.** The successor to IPv4, with 128-bit addresses, a simpler header and built-in autoconfiguration. It became an internet standard in 2017 (RFC 8200). + +See also: [IPv4](#ipv4), [ICMPv6](#icmpv6), [DNS - AAAA](d-f.md#dns-aaaa). + +### ISDN +**Integrated Services Digital Network.** A set of standards for digital voice and data over the telephone network, using 64 kbit/s channels with separate signalling. It was sold as basic rate (BRI) and primary rate (PRI) access. + +See also: [BRI](a-c.md#bri), [PRI](o-r.md#pri), [Q.931](o-r.md#q931), [ISDN2](#isdn2), [ISDN30](#isdn30). + +### ISDN2 +BT's name for ISDN basic rate access: two 64 kbit/s channels. See [BRI](a-c.md#bri). + +### ISDN30 +BT's name for ISDN primary rate access: up to 30 channels on a 2 Mbit/s line. See [PRI](o-r.md#pri). + +### ISO + +**International Organization for Standardization.** + +The international body made up of national standards bodies, such as BSI and ANSI, that publishes standards in almost every field. + +See also: [IEC](#iec), [ANSI](a-c.md#ansi). + +### ISP +**Internet Service Provider.** A company that provides internet access, and often related services such as email, hosting and domain registration. + +### Issue +Something that needs resolving and could affect the project if left. In this sense it is not already covered by the plan, a change request, a defect or a risk. + +See also: [Issue Management](#issue-management), [Issue tracker](#issue-tracker). + +### Issue Management +Recording, tracking and resolving a project's issues. + +See also: [Issue](#issue). + +### Issue tracker +Software that records issues, such as bugs, tasks or support requests, and tracks them from report to resolution. + +See also: [Defect Management](d-f.md#defect-management). + +### ISUP +**ISDN User Part.** The SS7 protocol that sets up and clears telephone calls between exchanges, carrying details such as the called number. It is defined in the ITU-T Q.76x series. + +See also: [SS7](s-z.md#ss7), [IUP](#iup), [TUP](s-z.md#tup). + +### ITIL +A widely used framework of good practice for IT service management, covering how services are designed, delivered, run and improved. The name came from the Information Technology Infrastructure Library. + +See also: [CMDB](a-c.md#cmdb), [CCTA](a-c.md#ccta). + +### ITU +**International Telecommunication Union.** The United Nations agency for information and communication technologies. It coordinates the radio spectrum and satellite orbits, and sets telecoms standards through ITU-T. + +See also: [ITU-T](#itu-t), [ETSI](d-f.md#etsi). + +### ITU-T +The ITU's standardisation sector, which publishes telecoms standards as Recommendations, such as G.711 and H.323. It was called the CCITT until 1993. + +See also: [ITU](#itu), [CCITT](a-c.md#ccitt). + +### IUP +**Interconnect User Part.** The UK national version of SS7 call signalling between operators' networks, formerly called BTNUP. + +See also: [ISUP](#isup), [BTNUP](a-c.md#btnup). + +### IVR +**Interactive Voice Response.** A telephone system that talks to callers with recorded or generated speech and responds to their key presses or spoken answers, typically to route calls or serve simple requests. + +See also: [DTMF](d-f.md#dtmf). + +### Item +In a backlog or tracker, one unit of work being managed, such as a change request, defect, risk or issue. + +See also: [Work Item](s-z.md#work-item). + +### Iteration +A fixed period, or timebox, in which a team develops and delivers a working increment. + +See also: [Sprints](s-z.md#sprints), [Timebox](s-z.md#timebox). + +### Iterative Development +Developing by repeating cycles of work and deliberately revisiting earlier work in the light of feedback, rather than doing each step once. + +See also: [Incremental Development](#incremental-development), [Refactoring](o-r.md#refactoring). + +## J + +### Java +A class-based, object-oriented language released by Sun Microsystems in 1995. It compiles to bytecode that runs on the Java virtual machine, so the same code runs on any platform that has one. + +See also: [JavaScript](#javascript), [C#](a-c.md#c_2). + +### JavaScript +The scripting language of the web, run by every browser and, through Node.js, on servers. It is dynamic and supports object-oriented, functional and event-driven styles. It is standardised as ECMAScript. + +See also: [JSON](#json), [Java](#java). + +### Jitter +Variation in the timing of a signal or in the delay of packets. In packet networks it is also called packet delay variation, and it affects real-time traffic such as voice and video. + +See also: [Jitter buffer](#jitter-buffer), [Latency](l-n.md#latency). + +### Jitter buffer +A buffer at a receiver that holds arriving voice or video packets for a short time, so they can be played out at an even rate despite jitter. Adaptive buffers change their size to match conditions, trading delay against loss. + +See also: [Jitter](#jitter), [RTP](o-r.md#rtp). + +### Joint Application Development +**JAD.** A facilitated workshop in which customer representatives and developers draft requirements together. + +See also: [RAD](o-r.md#rad). + +### JSON +**JavaScript Object Notation.** A lightweight text format for data made of objects (name and value pairs) and arrays, defined in RFC 8259. It is the usual format for web APIs. + +See also: [JSON-RPC](#json-rpc), [YAML](s-z.md#yaml), [XML](s-z.md#xml), [CBOR](a-c.md#cbor). + +### JSON-RPC +A simple remote procedure call protocol that encodes calls and results in JSON. + +See also: [XML-RPC](s-z.md#xml-rpc), [RPC](o-r.md#rpc). + +## K + +### K & R {#k-r} +**Kernighan and Ritchie.** Brian Kernighan and Dennis Ritchie of Bell Labs, authors of *The C Programming Language* (1978). Ritchie created C and, with Ken Thompson, Unix. + +See also: [K & R C](#k-r-c), [C Language](a-c.md#c-language). + +### K & R C {#k-r-c} +The version of C described in the first edition of Kernighan and Ritchie's book, which served as its informal specification before the ANSI standard of 1989. + +See also: [K & R](#k-r), [C Language](a-c.md#c-language). + +### K & R indent style {#k-r-indent-style} +The brace style used in Kernighan and Ritchie's book. A function's opening brace goes on its own line, while blocks inside the function open on the same line as their control statement. + +See also: [Construction Standard](a-c.md#construction-standard). + +### Kanban +A method for managing knowledge work by making the workflow visible, limiting work in progress and improving the flow step by step. + +See also: [Kanban Board](#kanban-board), [Lean](l-n.md#lean). + +### Kanban Board +A board with a column for each stage of a workflow, on which cards representing work items move from left to right. + +See also: [Kanban](#kanban), [Task Board](s-z.md#task-board). + +### KDL +A document language with XML-like semantics and a syntax that looks like a series of commands. It is used for configuration and data, like JSON, YAML or XML. + +See also: [YAML](s-z.md#yaml), [TOML](s-z.md#toml). + +### Kerberos +A network authentication protocol, developed at MIT, in which a trusted key distribution centre issues time-limited tickets. Clients and services then prove their identities to each other without sending passwords. Windows Active Directory uses it. + +See also: [AD](a-c.md#ad), [LDAP](l-n.md#ldap). + +### Kernel +The core of an operating system, which runs with full control of the hardware. It manages processes, memory, devices and system calls, and keeps applications apart from each other. + +See also: [Linux](l-n.md#linux), [Driver](d-f.md#driver). + +### KISS Principle +**Keep it simple, stupid.** The principle that most systems work best when kept simple, and that unnecessary complexity should be avoided. + +See also: [Rule of Simplicity](o-r.md#rule-of-simplicity), [Simple Design](s-z.md#simple-design). + +### Knowledge Management +**KM.** Capturing, sharing and reusing an organisation's knowledge so that people can find what they need. + +See also: [Wiki](s-z.md#wiki). + +### KPI +**Key Performance Indicator.** A measure of how well an organisation or activity is meeting an important goal. + +See also: [Metric](l-n.md#metric), [SLA](s-z.md#sla). + +### Ksh +The KornShell, a Unix shell written by David Korn at Bell Labs in the early 1980s. It is compatible with the Bourne shell and adds features from the C shell. + +See also: [Sh](s-z.md#sh), [Bash](a-c.md#bash), [Csh](a-c.md#csh). diff --git a/content/glossary/index.md b/content/glossary/index.md index 3dbe6b2..b168c47 100644 --- a/content/glossary/index.md +++ b/content/glossary/index.md @@ -5,6 +5,19 @@ author: Mark Bacon # Glossary -Terms used across software, IoT and architecture, A to Z. +Terms used across telecoms, networking, embedded and IoT engineering, software architecture and delivery, from A-law to ZigBee. -This section is moving in from technical-documentation's glossary and site-web-content-src's Glossary. +Each entry starts with a short definition. Acronyms give their expansion first, in bold. A sentence or two of detail follows where it helps, then links to related terms. The entries are deliberately short: they say what a term means and how it fits with the others, and leave the full story to the standards and books. + +| Section | Covers, for example | +| --- | --- | +| [A to C](a-c.md) | ATM, BGP, Bluetooth, C and C++, CDMA, change control, continuous integration | +| [D to F](d-f.md) | DNS and its records, DSL, DTLS, duplex, estimation, Ethernet, FOTA | +| [G to K](g-k.md) | G.711 and other codecs, GSM, HTTP, IMS, IPv4 and IPv6, ISDN, Kanban | +| [L to N](l-n.md) | L2TP, LTE, LwM2M, MPLS VPNs, MQTT, multicast, NAT | +| [O to R](o-r.md) | OSPF, PCM, PPP, QoS, REST, risk management, RTOS, RTP | +| [S to Z and numbers](s-z.md) | Scrum, SIP, SS7, TCP, TLS, UML, VLANs, Wi-Fi, 5G, 802.11 | + +[[CAPTION:Table]] The sections of the glossary. + +Search finds any term; on the sites, press `/` or `Ctrl+K`. diff --git a/content/glossary/l-n.md b/content/glossary/l-n.md new file mode 100644 index 0000000..bbc1c6d --- /dev/null +++ b/content/glossary/l-n.md @@ -0,0 +1,685 @@ +--- +title: Glossary, L to N +--- + +# L to N + +## L + +### L1 +**Layer 1, the physical layer.** The lowest layer of the OSI model, which sends raw bits over a medium such as copper, fibre or radio. It defines the connectors, signals, timing and encoding. + +See also: [L2](#l2), [Hub](g-k.md#hub). + +### L2 +**Layer 2, the data link layer.** The OSI layer that moves frames between devices on the same link or LAN segment, with local (MAC) addressing and error detection. Ethernet and Wi-Fi work here; switches forward traffic at this layer. + +See also: [L1](#l1), [MAC](#mac), [Switch](s-z.md#switch), [DLP](d-f.md#dlp). + +### L2F +**Layer 2 Forwarding.** A Cisco tunnelling protocol for carrying PPP sessions across an IP network. It has no encryption of its own, and L2TP replaced it. + +See also: [L2TP](#l2tp), [PPTP](o-r.md#pptp). + +### L2TP +**Layer 2 Tunnelling Protocol.** A protocol that tunnels PPP sessions over an IP network, used by ISPs to hand broadband sessions between networks and to build VPNs. It does not encrypt, so it is often run inside IPsec. + +See also: [LAC](#lac), [LNS](#lns), [LTS](#lts), [IPSec](g-k.md#ipsec). + +### L2VPN +**Layer 2 VPN.** A provider service that carries a customer's Ethernet or other layer-2 traffic between sites over the provider's MPLS network. The sites then appear to share one LAN or wire. Point-to-point and multipoint (VPLS) forms exist. + +See also: [VPLS](s-z.md#vpls), [VPWS](s-z.md#vpws), [L3VPN](#l3vpn), [PW](o-r.md#pw). + +### L3VPN +**Layer 3 VPN.** A provider service, usually MPLS-based as in RFC 4364, that routes a customer's IP traffic between sites. The provider edge routers keep each customer's routes in a separate VRF; customer edge routers connect to them, and provider core routers just switch labels. + +See also: [VRF](s-z.md#vrf), [CE](a-c.md#ce), [L2VPN](#l2vpn), [LSP](#lsp). + +### LAC +**L2TP Access Concentrator.** The device at one end of an L2TP tunnel that receives a user's PPP session and forwards it through the tunnel to the LNS. + +See also: [L2TP](#l2tp), [LNS](#lns). + +### LACP +**Link Aggregation Control Protocol.** The IEEE 802.1AX (formerly 802.3ad) protocol with which two devices agree to bundle several physical links into one logical link and check that each member is working. + +See also: [LAG](#lag). + +### LAG +**Link Aggregation Group.** Several physical links bundled into one logical link, to add capacity and survive the failure of a member. LACP usually manages it. + +See also: [LACP](#lacp). + +### LAN +**Local Area Network.** A network that connects devices within a limited area, such as a home, office or campus, usually with Ethernet and Wi-Fi. + +See also: [WAN](s-z.md#wan), [MAN](#man). + +### LANE +**LAN Emulation.** An ATM Forum standard that made an ATM network look like an Ethernet or Token Ring LAN to the devices attached to it. + +See also: [ATM](a-c.md#atm). + +### Latency +The delay between something being sent and it arriving. For telephone calls it is the mouth-to-ear delay, made up of codec, network and playout delays. ITU-T G.114 advises keeping one-way delay under about 150 ms for good conversation. + +See also: [Jitter](g-k.md#jitter), [Jitter buffer](g-k.md#jitter-buffer), [Bandwidth](a-c.md#bandwidth). + +### Lawful intercept +**LI.** Facilities in telecoms networks that let authorised agencies, with a warrant, intercept a named target's communications. Operators must provide them, through standardised interfaces. It differs from bulk surveillance in being targeted at individuals. + +### LCR +**Least Cost Routing.** Choosing the route for each outgoing call by cost, across several carriers. Carriers revise their tables often, and PBXs can do the same for a business. + +See also: [CPS](a-c.md#cps). + +### LDAP +**Lightweight Directory Access Protocol.** An open protocol, defined in RFC 4511, for reading and updating directory services, such as a company's directory of users and groups. Active Directory supports it. + +See also: [AD](a-c.md#ad), [Kerberos](g-k.md#kerberos). + +### Lead Time +The time from a customer's request to its delivery. In software, often the time from a requirement being raised to it being met in production. + +See also: [Kanban](g-k.md#kanban). + +### Lean +A way of working, from Toyota's production system, that aims to deliver value to the customer by removing waste: anything that does not add value. + +See also: [Lean programming](#lean-programming), [Kanban](g-k.md#kanban). + +### Lean programming +Lean ideas applied to software development: removing waste, delivering fast, deciding as late as possible and building quality in. + +See also: [Lean](#lean). + +### Leased Line +A dedicated, symmetrical circuit between two points, rented for a fixed fee and always on. In the UK it is also called a private circuit. Businesses use leased lines to link sites and for internet access. + +See also: [EAD](d-f.md#ead), [Dark Fibre](d-f.md#dark-fibre), [CSI](a-c.md#csi). + +### LeSS +**Large-Scale Scrum.** A framework for scaling Scrum to many teams working on one product, with one product owner and one product backlog. + +See also: [Scrum](s-z.md#scrum), [SAFe](s-z.md#safe), [DAD](d-f.md#dad). + +### Lifecycle +A model of the activities from the first idea for a system to its retirement, usually divided into phases. Projects choose and tailor a lifecycle to suit their risks. + +See also: [Waterfall](s-z.md#waterfall), [Spiral Lifecycle](s-z.md#spiral-lifecycle), [SDLC](s-z.md#sdlc), [Phase](o-r.md#phase). + +### Lines of Code +**LOC.** A measure of software size as the number of source lines, usually counting neither comments nor blank lines. KLOC means thousands of lines. + +See also: [Function Point](d-f.md#function-point). + +### Linux +A family of free, open-source operating systems built on the Linux kernel, first released by Linus Torvalds in 1991. It is packaged in distributions, such as Debian, Ubuntu, Fedora and Red Hat Enterprise Linux. It runs most servers and embedded devices, and underlies Android. + +See also: [GNU](g-k.md#gnu), [Unix](s-z.md#unix), [Kernel](g-k.md#kernel), [Android](a-c.md#android). + +### Lisp +A family of languages, first specified in 1958, with a fully bracketed prefix syntax in which code and data share the same form. Common Lisp, Scheme and Clojure are its main dialects. Lisp introduced many ideas now common, such as garbage collection and the read-eval-print loop. + +### LL +See [Local Loop](#local-loop). + +### LNS +**L2TP Network Server.** The device at the far end of an L2TP tunnel from the LAC, which terminates the users' PPP sessions, typically at the ISP. + +See also: [L2TP](#l2tp), [LAC](#lac), [LTS](#lts). + +### Local Build +A build done in a developer's local development environment. + +See also: [Project Build](o-r.md#project-build), [Build](a-c.md#build). + +### Local Development Environment +**LDE.** A developer's own development environment, usually on their own machine. + +See also: [Development Environment](d-f.md#development-environment), [Build Environment](a-c.md#build-environment). + +### Local Loop +The line that connects a customer's premises to the operator's network, traditionally a copper pair to the local exchange. Also called the last mile or subscriber line. + +See also: [MPF](#mpf), [MDF](#mdf), [DP](d-f.md#dp). + +### Local Test Environment +The part of the local development environment used for construction testing. + +See also: [Local Development Environment](#local-development-environment). + +### LoFi Prototype +See [Low Fidelity Prototype](#low-fidelity-prototype). + +### Low Fidelity Prototype +A rough mock-up of a system made with paper, sticky notes or simple drawings, used to explore ideas cheaply before building anything. + +See also: [High Fidelity Prototype](g-k.md#high-fidelity-prototype), [Storyboard](s-z.md#storyboard). + +### Low Level Design +**LLD.** The design level between high-level design and construction, detailed enough to build from directly. + +See also: [High Level Design](g-k.md#high-level-design), [Detailed Design](d-f.md#detailed-design). + +### LSP +**Label Switched Path.** A path through an MPLS network, set up by a protocol such as LDP or RSVP-TE. The first router adds a label, each router along the way swaps it, and the last removes it. + +See also: [LSR](#lsr), [RSVP](o-r.md#rsvp), [L3VPN](#l3vpn). + +### LSR +**Label Switch Router.** A router in the middle of an MPLS network that forwards packets by their labels alone. + +See also: [LSP](#lsp). + +### LTE (4G) +**Long-Term Evolution.** The 3GPP mobile standard (Release 8 onwards) that followed UMTS, with an OFDMA radio interface and an all-IP core, the Evolved Packet Core. LTE-Advanced meets the ITU's 4G requirements. Voice runs over IP as VoLTE. + +See also: [E-UTRAN](d-f.md#e-utran), [E NodeB](d-f.md#e-nodeb), [MME](#mme), [S-GW](s-z.md#s-gw), [PGW](o-r.md#pgw), [VoLTE](s-z.md#volte). + +### LTS +**L2TP Tunnel Switch.** A router between a LAC and an LNS that acts as both. It ends incoming L2TP tunnels and forwards the sessions through new tunnels to other LNSs, for example to different ISPs. + +See also: [L2TP](#l2tp), [LAC](#lac), [LNS](#lns). + +### Lua +A small, fast scripting language from Brazil, designed in 1993 to be embedded in applications through a simple C API. It is used widely in games and network equipment. + +### LwM2M +**Lightweight Machine to Machine.** The OMA SpecWorks protocol for managing IoT devices and their data over CoAP, usually secured with DTLS. Devices expose standard objects, such as device information, connectivity and firmware update, so servers can manage different makers' devices in the same way. + +See also: [M2M](#m2m), [DTLS](d-f.md#dtls), [CBOR](a-c.md#cbor), [FOTA](d-f.md#fota). + +## M + +### M2M +**Machine to Machine.** Direct communication between devices, such as meters, sensors and vehicles, and the systems that use their data, without people in the loop. It was the forerunner of the Internet of Things. + +See also: [LwM2M](#lwm2m), [MQTT](#mqtt). + +### MAC +**Medium Access Control.** The lower sublayer of the data link layer in IEEE 802 networks. It controls access to the shared medium and handles framing and hardware addressing; the logical link control (LLC) sublayer sits above it. + +See also: [MAC Address](#mac-address), [L2](#l2), [CSMA](a-c.md#csma). + +### MAC Address +**Media Access Control address.** The 48-bit hardware address of a network interface on Ethernet, Wi-Fi and other IEEE 802 networks. It is written as six hex pairs, such as `00:1A:2B:3C:4D:5E`. The first half normally identifies the manufacturer. + +See also: [MAC](#mac), [MAC Spoofing](#mac-spoofing), [ARP spoofing](a-c.md#arp-spoofing). + +### MAC Flooding +An attack that fills a switch's address table with fake MAC addresses. The switch then floods frames out of every port, letting the attacker see traffic meant for others. + +See also: [Switch](s-z.md#switch), [MAC Spoofing](#mac-spoofing). + +### MAC Spoofing +Changing the MAC address a network interface presents, usually through its driver, to pose as another device or hide its identity. + +See also: [MAC Address](#mac-address), [ARP spoofing](a-c.md#arp-spoofing). + +### Machine code +Instructions in the binary form a processor runs directly. People rarely write it by hand: compilers and assemblers produce it. + +See also: [Compiler](a-c.md#compiler), [Compiled Language](a-c.md#compiled-language). + +### Macro Estimation +Estimating something as a whole. See [Top-Down Estimation](s-z.md#top-down-estimation). + +### Maintenance +Software maintenance: correcting, updating, adapting and operating software after its first release. + +See also: [Maintenance Plan](#maintenance-plan). + +### Maintenance Plan +A plan for maintaining a system after its first release. + +### MAN +**Metropolitan Area Network.** A network that covers a city or region: larger than a LAN, smaller than a WAN, and often linking several LANs. + +See also: [LAN](#lan), [WAN](s-z.md#wan). + +### Management by Walking Around +**MBWA.** Managing through frequent, informal contact with the team, alongside formal tracking, to spot risks and problems early. + +### Management Plane +The part of a network device or network that configures, monitors and manages it, through interfaces such as the CLI, SNMP or NETCONF. + +See also: [Control Plane](a-c.md#control-plane), [Data Plane](d-f.md#data-plane), [SNMP](s-z.md#snmp). + +### MANET +**Mobile Ad hoc Network.** A self-configuring wireless network of mobile devices with no fixed infrastructure, in which every device also routes traffic for the others. + +See also: [WANET](s-z.md#wanet), [Wireless Mesh Network](s-z.md#wireless-mesh-network), [Geocast](g-k.md#geocast). + +### Manual Testing +Testing in which a person runs the test cases and records the results. + +See also: [Automated Testing](a-c.md#automated-testing). + +### MAP +**Mobile Application Part.** The SS7 protocol with which GSM and UMTS core network nodes, such as the HLR, VLR, MSC and SGSN, exchange information. It covers location updates, authentication and SMS delivery. + +See also: [SS7](s-z.md#ss7), [HLR](g-k.md#hlr), [VLR](s-z.md#vlr), [TCAP](s-z.md#tcap). + +### MBMS +**Multimedia Broadcast Multicast Services.** 3GPP standards for broadcasting and multicasting content to many mobile devices at once. In LTE it is called eMBMS or LTE Broadcast. + +See also: [Multicast](#multicast), [LTE (4G)](#lte-4g). + +### MBORC +**Matters Beyond Our Reasonable Control.** A clause in Openreach contracts that relieves Openreach of its service-level obligations when an outside event, such as severe weather or third-party damage, prevents it from meeting them. + +### MCU +**Microcontroller Unit.** A single chip with a processor core, flash and RAM, and peripherals, used in small embedded devices. It usually runs bare-metal code or an RTOS. + +See also: [MPU](#mpu), [RTOS](o-r.md#rtos), [Embedded systems programming](d-f.md#embedded-systems-programming). + +### MD5 +**Message Digest 5.** A 128-bit hash function from 1991. It is broken for security uses because collisions are easy to make, so it should be used only as a checksum against accidental corruption. + +See also: [SHA](s-z.md#sha), [Hash Function](g-k.md#hash-function). + +### MDF +**Main Distribution Frame.** The frame in a telephone exchange where the external cables to customers are connected to the exchange's equipment by jumpers. + +See also: [HDF](g-k.md#hdf), [Local Loop](#local-loop), [MPF](#mpf). + +### Mediation +In telecoms, the systems that collect usage records, such as CDRs, from network elements, then clean, combine and convert them into the formats that billing, fraud and other systems need. + +See also: [CDR](a-c.md#cdr), [OSS](o-r.md#oss). + +### MELP +**Mixed-Excitation Linear Prediction.** A US military speech codec standard. Its enhanced version, MELPe, works at 2,400, 1,200 or 600 bit/s for secure and narrow-band radio links. + +See also: [CVSD](a-c.md#cvsd), [Audio Codecs](a-c.md#audio-codecs). + +### Metric +A measurement taken from a project, process or product to judge whether it has the qualities wanted. + +See also: [KPI](g-k.md#kpi). + +### MGCF +**Media Gateway Control Function.** In IMS, the function that converts call signalling between SIP and the circuit-switched network's ISUP or BICC, and controls the media gateway through H.248. + +See also: [MGW](#mgw), [IMS](g-k.md#ims), [BGCF](a-c.md#bgcf). + +### MGCP +**Media Gateway Control Protocol.** A VoIP protocol in which a central call agent controls simple media gateways and endpoints. It is an IETF informational RFC; H.248 is the formal standard for the same role. + +See also: [H.248](g-k.md#h248), [Softswitch](s-z.md#softswitch). + +### MGW +**Media Gateway.** A device that converts media between networks, typically between PCM on telephone circuits and RTP streams on IP. It also transcodes when the two sides use different codecs. + +See also: [MGCF](#mgcf), [H.248](g-k.md#h248), [RTP](o-r.md#rtp). + +### MIB +**Management Information Base.** The tree-structured set of objects that a device exposes for management, mostly through SNMP. Each object is identified by an object identifier (OID). + +See also: [SNMP](s-z.md#snmp). + +### Micro Estimation +Estimating the details of something. See [Bottom-Up Estimation](a-c.md#bottom-up-estimation). + +### Microservice +An architecture style in which an application is a set of small services, each built around a business capability. Each can be deployed independently and communicates through lightweight APIs. It suits large systems with many teams, at the cost of operational complexity. + +See also: [SOA](s-z.md#soa), [BFF](a-c.md#bff), [Docker](d-f.md#docker). + +### Microstone +See [Miniature Milestone](#miniature-milestone). + +### Mil-COTS +COTS products for military use. See [COTS](a-c.md#cots). + +### Milestone +A significant point in a schedule, such as an achievement or a date. + +See also: [Miniature Milestone](#miniature-milestone), [Business Schedule](a-c.md#business-schedule). + +### Milestone Release +A release made for a milestone in the project plan. + +### Milestone Retrospective +A detailed review by the team of a project's significant events, after a major milestone or at the end of the project. + +See also: [Postmortem](o-r.md#postmortem), [Sprint retrospective](s-z.md#sprint-retrospective). + +### Milestone Schedule +A business schedule that sets out the project's formal milestones. + +See also: [Business Schedule](a-c.md#business-schedule). + +### MIMO +**Multiple-Input, Multiple-Output.** Using several antennas at both ends of a radio link to send several data streams at once over the same channel, exploiting multipath propagation. Wi-Fi, LTE and 5G all rely on it. + +See also: [SISO](s-z.md#siso), [SDMA](s-z.md#sdma), [Wi-Fi](s-z.md#wi-fi). + +### Miniature Milestone +A small milestone, a day or two of work, that counts as either done or not done, never partly done. It makes progress easy to track. + +See also: [Milestone](#milestone), [Inch-Pebble](g-k.md#inch-pebble). + +### MME +**Mobility Management Entity.** The main control node of the LTE core. It authenticates users with the HSS, tracks and pages idle devices, chooses gateways and manages bearers and handovers. + +See also: [HSS](g-k.md#hss), [S-GW](s-z.md#s-gw), [E NodeB](d-f.md#e-nodeb), [LTE (4G)](#lte-4g). + +### MMF +**Minimum Marketable Feature.** The smallest feature that is worth releasing on its own because it gives users real value. + +See also: [MVP](#mvp). + +### MNC +**Mobile Network Code.** The two- or three-digit code that, with the mobile country code (MCC), identifies a mobile network. Both form the start of an IMSI. + +See also: [IMSI](g-k.md#imsi). + +### Mob Programming +The whole team working on the same thing, at the same time, in the same place, at one computer. + +See also: [Pair Programming](o-r.md#pair-programming). + +### Mobile Cell +The area served by one base station in a cellular network. Splitting coverage into cells lets the same frequencies be reused in cells further apart. Cell sizes range from a few metres to tens of kilometres. + +See also: [BTS](a-c.md#bts), [FemtoCell](d-f.md#femtocell). + +### Mock Objects +Stand-ins for real components, created for a test, that imitate the real behaviour and check how the code under test uses them. + +See also: [Unit Testing](s-z.md#unit-testing), [TDD](s-z.md#tdd). + +### Model +A simplified representation of a system or process, often as diagrams, that describes its important characteristics. + +See also: [Modelling](#modelling), [UML](s-z.md#uml). + +### Modelling +Using models in requirements and design work. + +See also: [Model](#model). + +### Moderator +The person who leads an inspection and makes sure it follows the process. + +See also: [Inspection](g-k.md#inspection). + +### MOS +**Mean Opinion Score.** A rating of perceived quality, especially of voice calls, on a scale from 1 (bad) to 5 (excellent). It is either the average of listeners' scores or estimated by an algorithm. ITU-T P.800 defines it. + +| MOS | Quality | Impairment | +| --- | --- | --- | +| 5 | Excellent | Imperceptible | +| 4 | Good | Perceptible but not annoying | +| 3 | Fair | Slightly annoying | +| 2 | Poor | Annoying | +| 1 | Bad | Very annoying | + +[[CAPTION:Table]] The MOS scale. + +See also: [Latency](#latency), [Jitter](g-k.md#jitter). + +### MP3 +**MPEG-1 or MPEG-2 Audio Layer III.** A lossy audio coding format that removes sounds people are unlikely to hear. It made music files small enough to share and became the most common format for digital music. + +See also: [AAC](a-c.md#aac), [MPEG](#mpeg). + +### MPEG +**Moving Picture Experts Group.** The ISO and IEC working group that sets standards for audio and video coding, such as MPEG-2 and MPEG-4. + +See also: [MPEG4](#mpeg4), [MP3](#mp3). + +### MPEG4 +**MPEG-4.** A family of ISO/IEC standards (14496) for coding audio and video. It includes AAC audio and the H.264 (AVC) video codec, widely used for streaming and broadcast. + +See also: [MPEG](#mpeg), [AAC](a-c.md#aac). + +### MPF +**Metallic Path Facility.** An Openreach product that gives another operator a whole copper line from the exchange to the customer, so the operator provides both voice and broadband. + +See also: [SMPF](s-z.md#smpf), [Local Loop](#local-loop), [MDF](#mdf). + +### MPU +**Microprocessor Unit.** A processor that relies on external memory and usually has a memory management unit, so it can run a full operating system such as Linux. + +See also: [MCU](#mcu). + +### MQTT +A lightweight publish-subscribe messaging protocol, over TCP, in which clients publish and subscribe to topics through a broker. It was designed in 1999 for low-bandwidth links, is an OASIS standard, and is widely used in IoT. + +See also: [M2M](#m2m), [LwM2M](#lwm2m). + +### MRF +**Media Resource Function.** In IMS, the function that plays announcements and tones, mixes conference audio and does other media processing. + +See also: [IMS](g-k.md#ims). + +### MRS +**Multiple Residence data.** Royal Mail address data that lists the separate homes, such as flats, behind a single delivery point. + +### MRTIE +**Maximum Relative Time Interval Error.** A measure of clock stability in synchronised networks: the largest change in a clock's time error against a reference over a given observation interval. + +See also: [PTP](o-r.md#ptp), [Jitter](g-k.md#jitter). + +### MSAN +**Multi-Service Access Node.** Equipment in an exchange or cabinet that connects customers' lines to the core network and provides voice, ISDN and broadband from one platform. It replaces separate exchange line cards and DSLAMs. + +See also: [DSLAM](d-f.md#dslam), [BT 21CN](a-c.md#bt-21cn), [NGN](#ngn). + +### MSC +**Mobile Switching Centre.** The switch in a GSM or UMTS core network that sets up and routes voice calls and SMS, handles handovers between areas and produces charging records. + +See also: [GMSC](g-k.md#gmsc), [HLR](g-k.md#hlr), [VLR](s-z.md#vlr), [BSC](a-c.md#bsc). + +### MTP +**Message Transfer Part.** The lower levels (1 to 3) of SS7, which carry signalling messages reliably and in order between signalling points. + +See also: [SS7](s-z.md#ss7), [SCCP](s-z.md#sccp). + +### MTR +**Mean Time to Repair (MTTR).** The average time taken to restore failed equipment or a service to working order. + +### MTU +**Maximum Transmission Unit.** The largest packet a network link can carry without fragmentation, 1,500 bytes on standard Ethernet. Tunnels add headers, so they reduce the usable MTU. + +See also: [PDU](o-r.md#pdu). + +### Mu-law +**µ-law.** A companding algorithm, one of the two variants of ITU-T G.711, used for 8-bit PCM speech in North America and Japan. It is also written u-law. + +See also: [A-law](a-c.md#a-law), [G.711](g-k.md#g711). + +### Multicast +Sending data to a group of receivers at once, with the network copying packets only where the paths divide. IPTV uses it, with receivers joining groups through IGMP. + +```mermaid +flowchart LR + S((Sender)) --> R1[Router] + R1 --> R2[Router] + R1 --> R3[Router] + R2 --> A((Member)) + R2 --> B((Member)) + R3 --> C((Member)) +``` + +[[CAPTION:Figure]] Multicast: one stream, copied only where the paths divide. + +See also: [Unicast](s-z.md#unicast), [Broadcast](a-c.md#broadcast), [Anycast](a-c.md#anycast), [IGMP](g-k.md#igmp). + +### Multiplex +Combining several signals or data streams onto one shared medium, by time, frequency, wavelength or code, and separating them again at the far end. + +See also: [TDM](s-z.md#tdm), [OFDMA](o-r.md#ofdma), [CDMA](a-c.md#cdma). + +### Mutex +A lock that lets only one thread at a time hold a shared resource, so threads cannot corrupt it by using it at once. + +See also: [Mutual Exclusion](#mutual-exclusion), [Semaphore](s-z.md#semaphore). + +### Mutual Exclusion +The requirement that only one thread at a time runs a critical section that uses a shared resource, to prevent race conditions. Edsger Dijkstra first described and solved the problem in 1965. + +See also: [Mutex](#mutex), [Semaphore](s-z.md#semaphore). + +### MVNE +**Mobile Virtual Network Enabler.** A company that provides MVNOs with the systems they need, such as billing, provisioning and network integration, without dealing with consumers itself. + +See also: [MVNO](#mvno). + +### MVNO +**Mobile Virtual Network Operator.** A mobile operator that sells services under its own brand but does not own the radio network. It buys capacity wholesale from a network operator. + +See also: [MVNE](#mvne). + +### MVP +**Minimum Viable Product.** The first version of a product built to learn as much as possible about customers with the least effort, as described by Eric Ries. + +See also: [MMF](#mmf), [Customer Development](a-c.md#customer-development). + +## N + +### NaaS +**Network as a Service.** Network connectivity, such as VPNs and bandwidth on demand, offered as a cloud-style service, often built on network virtualisation. + +See also: [IaaS](g-k.md#iaas), [SDN](s-z.md#sdn). + +### NAPT +**Network Address and Port Translation.** NAT that also rewrites port numbers, so that many private hosts can share one public IP address. It is also called PAT or IP masquerading. + +See also: [NAT](#nat). + +### NAS +**Network Access Server.** A device that gives users access to a network, such as a dial-up or broadband access server. It usually authenticates them through RADIUS. In LTE, NAS also stands for the non-access stratum: the signalling between the device and the core. + +See also: [Radius](o-r.md#radius), [BRAS](a-c.md#bras). + +### NAT +**Network Address Translation.** Rewriting IP addresses in packets as they pass through a router, usually so that a private network can share public addresses. It has kept IPv4 going despite address exhaustion, but it complicates peer-to-peer protocols. + +See also: [NAPT](#napt), [STUN](s-z.md#stun), [ICE](g-k.md#ice), [IPv4](g-k.md#ipv4). + +### Native Risk Management +See [Intrinsic Risk Management](g-k.md#intrinsic-risk-management). + +### NB-IoT +**Narrowband IoT.** A 3GPP low-power, wide-area radio technology for simple IoT devices, such as meters, that send little data and must run for years on a battery. + +See also: [LTE (4G)](#lte-4g), [LwM2M](#lwm2m). + +### NBAP +**Node B Application Part.** The UMTS signalling protocol on the Iub interface with which the RNC controls a Node B, setting up cells and radio links. + +See also: [Node B](#node-b), [RNC](o-r.md#rnc), [UTRAN](s-z.md#utran). + +### NCSC +**National Cyber Security Centre.** The UK's technical authority on cyber security, part of GCHQ, which advises government, businesses and the public. It opened in 2016. + +See also: [GCHQ](g-k.md#gchq), [CESG](a-c.md#cesg). + +### Network Topologies +The arrangement of a network's nodes and links, such as bus, star, ring, mesh or tree. The physical topology is how it is cabled; the logical topology is how data flows. + +```mermaid +flowchart LR + subgraph Star + H((Hub)) --- s1((A)) + H --- s2((B)) + H --- s3((C)) + end + subgraph Ring + r1((A)) --- r2((B)) --- r3((C)) --- r1 + end + subgraph Mesh + m1((A)) --- m2((B)) + m2 --- m3((C)) + m3 --- m1 + end +``` + +[[CAPTION:Figure]] Star, ring and mesh topologies. + +### NFS +**Network File System.** A protocol, first developed by Sun in 1984, that lets a computer use files on a remote server as if they were local. + +### NGN +**Next-Generation Network.** A packet-based network, usually all-IP, that carries every service, voice included, with service control separate from transport. ITU-T and ETSI TISPAN defined NGN architectures in the 2000s, and IMS became their service layer. + +See also: [IMS](g-k.md#ims), [BT 21CN](a-c.md#bt-21cn), [Softswitch](s-z.md#softswitch). + +### NGWFQ +A form of weighted fair queuing. Weighted fair queuing shares a link's capacity between flows or classes in proportion to weights set for each. + +See also: [PWFQ](o-r.md#pwfq), [QoS](o-r.md#qos). + +### Niko-niko Calendar +A calendar on which each team member records their mood each day, often with a smiley face, to show patterns in how the team feels. + +See also: [Information Radiators](g-k.md#information-radiators). + +### NIST +**National Institute of Standards and Technology.** The US agency that maintains measurement standards and publishes widely used computer security standards and guidance, such as FIPS and the SP 800 series. + +See also: [FIPS](d-f.md#fips), [AES](a-c.md#aes). + +### NNI +**Network-to-Network Interface.** The interface between two networks, or two parts of one network, with its signalling and management. It differs from the user-network interface (UNI), between a network and its customer. + +See also: [UNI](s-z.md#uni). + +### NNTP +**Network News Transfer Protocol.** The protocol, first defined in RFC 977 in 1986, for distributing, reading and posting Usenet news articles. + +### NOC +**Network Operations Centre.** The place from which an operator monitors and manages its network. + +### Node B +The UMTS base station, the equivalent of the GSM BTS. It handles the radio link with mobile devices, under the control of an RNC. + +See also: [RNC](o-r.md#rnc), [BTS](a-c.md#bts), [E NodeB](d-f.md#e-nodeb), [NBAP](#nbap). + +### Nominal Path +The path through a system's behaviour where everything goes as expected, with no errors or exceptions. Also called the happy path. + +See also: [Use Case](s-z.md#use-case), [Happy Path](g-k.md#happy-path). + +### Non-functional Requirement +A requirement about how well a system works rather than what it does, such as performance, reliability, security, usability or compatibility. Also called a quality attribute. + +See also: [Functional Requirement](d-f.md#functional-requirement), [How Requirement](g-k.md#how-requirement). + +### NoSQL +Databases that store data in forms other than relational tables, such as key-value, document, wide-column or graph stores. They often trade strict consistency for easier horizontal scaling. + +See also: [RDBMS](o-r.md#rdbms), [SQL](s-z.md#sql). + +### NPE +**Network Provider Edge.** A provider edge (PE) router, which connects customer networks or other providers' networks to a provider's core. + +See also: [CE](a-c.md#ce), [L3VPN](#l3vpn). + +### NSS +**Network Switching Subsystem.** The GSM core network: the MSCs, HLR, VLR and related nodes that switch calls and manage mobility. GPRS added a packet core alongside it. + +See also: [MSC](#msc), [HLR](g-k.md#hlr), [GSM](g-k.md#gsm). + +### NTP +**Network Time Protocol.** The protocol that synchronises computer clocks over packet networks. It gets within tens of milliseconds of UTC over the internet, and usually within a millisecond on a LAN. + +See also: [SNTP](s-z.md#sntp), [PTP](o-r.md#ptp), [UTC](s-z.md#utc). + +### NTS +**Number Translation Service.** A non-geographic number, such as a UK 08 number, that the network translates to an ordinary number, so the destination can change without changing the published number. + +See also: [IN](g-k.md#in). + +### NTU +**Network Terminating Unit.** The device that marks the boundary between the operator's line and the customer's equipment, and gives a point for testing the line. + +See also: [CPE](a-c.md#cpe). + +### NYB +**Not Yet Built.** Royal Mail address data for properties that are planned or under construction. diff --git a/content/glossary/o-r.md b/content/glossary/o-r.md new file mode 100644 index 0000000..9bcd7e5 --- /dev/null +++ b/content/glossary/o-r.md @@ -0,0 +1,809 @@ +--- +title: Glossary, O to R +--- + +# O to R + +## O + +### Objective C +An object-oriented language that adds Smalltalk-style messaging to C. It was Apple's main language for macOS and iOS apps until Swift arrived. + +See also: [Swift](s-z.md#swift), [C Language](a-c.md#c-language). + +### Objectives +See [Goals](g-k.md#goals). + +### ODF +**Optical Distribution Frame.** A frame that terminates fibre cables and lets connections between them be made and changed with patch leads. + +See also: [MDF](l-n.md#mdf), [OFC](#ofc). + +### OFC +**Optical Fibre Connector.** A connector that joins optical fibres, aligning their cores so light passes with little loss. It is quicker to connect and disconnect than a splice. Common types include LC, SC and ST. + +See also: [ODF](#odf). + +### Ofcom +**Office of Communications.** The UK regulator for broadcasting, telecoms, post and the radio spectrum, set up under the Communications Act 2003. + +### OFDMA +**Orthogonal Frequency-Division Multiple Access.** The multi-user form of OFDM, in which different users get different sets of closely spaced subcarriers at the same time. LTE downlinks, 5G and Wi-Fi 6 use it. + +See also: [SC-FDMA](s-z.md#sc-fdma), [COFDM](a-c.md#cofdm), [LTE (4G)](l-n.md#lte-4g). + +### OO +**Object-Oriented.** A paradigm that organises software around objects, which bundle data with the code that acts on it. Most OO languages are class-based, with inheritance and polymorphism. + +See also: [Programming paradigm](#programming-paradigm), [Polymorphism](#polymorphism), [UML](s-z.md#uml). + +### Operations Plan +A plan for running a system after deployment: roles, responsibilities, procedures and maintenance schedules. + +See also: [Deployment Plan](d-f.md#deployment-plan), [Maintenance Plan](l-n.md#maintenance-plan). + +### OPUS +**Opus.** An open, royalty-free audio codec, standardised by the IETF in RFC 6716. It combines the SILK speech coder with the CELT low-delay coder and adapts from narrowband speech to full-band music. It is the standard codec for WebRTC. + +See also: [SPEEX](s-z.md#speex), [Vorbis](s-z.md#vorbis), [Audio Codecs](a-c.md#audio-codecs). + +### OS X +**macOS.** Apple's operating system for Mac computers, released in 2001 as Mac OS X and renamed OS X and then macOS. It is a Unix system built on the Darwin kernel. + +See also: [Unix](s-z.md#unix). + +### OSA-FC +**Optical Spectrum Access Filter Connect.** An Openreach service that gives a provider a managed fibre connection on which it runs its own optical equipment. It works like dark fibre, but Openreach monitors and repairs the link. + +See also: [Dark Fibre](d-f.md#dark-fibre), [EAD](d-f.md#ead). + +### OSPF +**Open Shortest Path First.** A link-state interior gateway protocol: each router learns the whole topology of its area and calculates the shortest paths. Version 2 (RFC 2328) is for IPv4 and version 3 for IPv6. + +See also: [IGP](g-k.md#igp), [RIP](#rip), [BGP](a-c.md#bgp). + +### OSS +**Operations Support Systems.** The systems a telecoms operator uses to run its network, such as inventory, provisioning, configuration, fault and performance management. They work with the business support systems (BSS). + +See also: [BSS](a-c.md#bss), [Mediation](l-n.md#mediation). + +### OTN +**Optical Transport Network.** The ITU-T G.709 standard for carrying client signals, such as Ethernet or SDH, over wavelengths. It adds framing, forward error correction and management to optical networks. + +See also: [SDH](s-z.md#sdh). + +### Out-of-order delivery +Packets arriving in a different order from the one in which they were sent, for example because they took different paths. TCP puts the data back in order; real-time protocols must cope with it. + +See also: [TCP](s-z.md#tcp), [Jitter buffer](g-k.md#jitter-buffer). + +### Overlap Dialling +Sending a dialled number in pieces as the caller enters it, rather than all at once, so that routing can begin before the number is complete. The far end waits for more digits until a timer runs out. + +See also: [ISUP](g-k.md#isup), [Q.931](#q931). + +## P + +### PaaS +**Platform as a Service.** Cloud computing that provides a managed platform for building and running applications, so the customer does not manage servers or operating systems. + +See also: [IaaS](g-k.md#iaas), [SaaS](s-z.md#saas). + +### Packet sniffing +Capturing and decoding the packets crossing a network, usually with a packet analyser such as Wireshark, to troubleshoot problems or, in an attack, to steal data. + +See also: [Wireshark](s-z.md#wireshark), [DPI](d-f.md#dpi). + +### Packet Switched +A network that splits data into packets, each with a header that routers use to forward it independently, sharing links with other traffic. The internet works this way. + +See also: [Circuit Switched](a-c.md#circuit-switched). + +### PAF +**Postcode Address File.** Royal Mail's database of every UK delivery address and its postcode. + +### Pair Programming +Two developers working together at one computer: one writes the code while the other reviews it and thinks ahead, and they swap often. + +See also: [Mob Programming](l-n.md#mob-programming), [XP](s-z.md#xp). + +### PAP +**Password Authentication Protocol.** A simple PPP authentication method that sends the username and password in clear text. It should be used only when nothing stronger, such as CHAP or EAP, is available. + +See also: [CHAP](a-c.md#chap), [PPP](#ppp). + +### Parametric Estimation +Estimating with a model that calculates effort, cost or schedule from input factors, using formulas based on historical data. COCOMO is an example. + +See also: [Estimation](d-f.md#estimation), [Statistical Estimation](s-z.md#statistical-estimation). + +### Pascal +A procedural language designed by Niklaus Wirth around 1970 to teach structured programming. Object Pascal and Delphi descend from it. + +See also: [Delphi](d-f.md#delphi), [Ada](a-c.md#ada). + +### Pattern +A reusable template or model for creating an artefact or solving a recurring problem. + +See also: [Design Pattern](d-f.md#design-pattern), [Antipattern](a-c.md#antipattern). + +### PCM +**Pulse-Code Modulation.** The standard way of representing an analogue signal digitally: sample it at regular intervals and quantise each sample to a binary value. Telephone speech uses 8,000 samples a second at 8 bits (G.711), and CDs use 44,100 at 16 bits. + +See also: [G.711](g-k.md#g711), [A-law](a-c.md#a-law), [Mu-law](l-n.md#mu-law). + +### PCP +**Primary Connection Point.** The green roadside cabinet in the UK access network where the main cables from the exchange connect to the cables to local distribution points. Fibre-to-the-cabinet equipment sits next to it. + +In Ethernet, PCP also means the **Priority Code Point**: the 3-bit priority field in an 802.1Q tag. + +See also: [DP](d-f.md#dp), [VDSL](s-z.md#vdsl), [Dot1Q](d-f.md#dot1q). + +### PCRF +**Policy and Charging Rules Function.** The node in a mobile core that decides, in real time, the policy and charging rules for each subscriber's data sessions, such as quality of service and usage limits. The gateways then enforce them. + +See also: [PGW](#pgw), [QoS](#qos). + +### PCS +**Physical Coding Sublayer.** The top sublayer of the Ethernet physical layer, which encodes and decodes data, for example with 8b/10b or 64b/66b coding, and scrambles it. + +See also: [L1](l-n.md#l1). + +### PDCP +**Packet Data Convergence Protocol.** A 3GPP radio protocol layer, in UMTS, LTE and 5G, that compresses headers, ciphers data and delivers packets in order between the device and the base station. + +See also: [RRC](#rrc), [E-UTRAN](d-f.md#e-utran). + +### PDH +**Plesiochronous Digital Hierarchy.** The older digital transmission hierarchy. Links such as E1 (2 Mbit/s) and E3 run at nearly, but not exactly, the same rates and are multiplexed by bit stuffing. SDH replaced it in backbones. + +See also: [SDH](s-z.md#sdh), [TDM](s-z.md#tdm). + +### PDU +**Protocol Data Unit.** The unit of data a protocol layer exchanges with its peer. It is a frame at layer 2, a packet at layer 3, and a segment (TCP) or datagram (UDP) at layer 4. + +See also: [MTU](l-n.md#mtu). + +### PEAP +**Protected EAP.** An EAP method that sets up a TLS tunnel first and then runs a simpler authentication, often a password, inside it. It is common for Wi-Fi in organisations. + +See also: [EAP](d-f.md#eap), [TLS](s-z.md#tls). + +### Peer review +Checking work by people with similar skills and roles, to see that it meets its criteria. + +See also: [Review](#review). + +### Pen testing +**Penetration testing.** An authorised simulated attack on a system to find vulnerabilities that a real attacker could exploit. Testers may get full information about the system (white box) or none (black box). + +See also: [Ethical Hacking](d-f.md#ethical-hacking). + +### PER +**Packed Encoding Rules.** Compact ASN.1 encoding rules that use the limits in the schema to encode values in as few bits as possible. The decoder needs the schema. Mobile radio protocols such as RRC use PER. + +See also: [ASN.1](a-c.md#asn1), [BER](a-c.md#ber). + +### Performance +How well a system does what it does, such as speed, resource use, reliability and availability. The term is sometimes also used for the mix of features and quality a project delivers. + +See also: [Non-functional Requirement](l-n.md#non-functional-requirement). + +### Perl +A general-purpose scripting language created by Larry Wall in 1987, strong at text processing. Raku began as Perl 6 and became a separate language. + +See also: [Awk](a-c.md#awk), [Sed](s-z.md#sed). + +### Personas +Short, fictional profiles of typical users, used to keep their goals and needs in mind during design. + +See also: [User Experience](s-z.md#user-experience). + +### Perspective +In an inspection, a point of view given to an inspector, such as the tester's or the maintainer's, so that different inspectors find different issues. + +See also: [Inspection](g-k.md#inspection). + +### PERT chart + +**Program Evaluation and Review Technique.** + +A project planning technique, developed by the US Navy in the 1950s, that shows tasks as a network of dependencies. It estimates each task's duration from optimistic, likely and pessimistic values. + +See also: [CPM](a-c.md#cpm), [Gantt chart](g-k.md#gantt-chart). + +### PGP +**Pretty Good Privacy.** Encryption software, created by Phil Zimmermann in 1991, for signing and encrypting email and files. The OpenPGP standard (RFC 4880) describes its format. + +### PGW +**Packet Data Network Gateway.** The LTE core gateway that connects devices to external packet networks, such as the internet. It allocates IP addresses, enforces policy and charging, and anchors mobility. + +See also: [S-GW](s-z.md#s-gw), [PCRF](#pcrf), [GGSN](g-k.md#ggsn), [APN](a-c.md#apn). + +### Phase +A group of activities in a lifecycle, or a period in a schedule, often marking a major transition in a project. Sometimes used to mean a stage. + +See also: [Stage](s-z.md#stage), [Lifecycle](l-n.md#lifecycle). + +### Phased Estimation +Re-estimating throughout a project's lifecycle, using the techniques that best suit each phase. + +See also: [Estimation](d-f.md#estimation). + +### PHP +A server-side scripting language for the web, created by Rasmus Lerdorf in 1994. Its code can be embedded in HTML pages, and it powers many content management systems. + +### Planning and Tracking Lead +**PTL.** The person responsible for planning a project's technical work and tracking it: work breakdown, estimation, scheduling and progress. + +### Planning Poker +An agile estimation technique in which each team member chooses a card for their estimate and all reveal at once. Differences are then discussed and the round repeated until the estimates converge. + +See also: [Points](#points), [Relative Estimation](#relative-estimation). + +### PLL +**Phase-Locked Loop.** A control circuit that adjusts an oscillator so that its output stays in phase with a reference signal. PLLs are used for clock recovery, frequency synthesis and synchronisation. + +See also: [Jitter](g-k.md#jitter). + +### PNT +**Pointer.** Ordnance Survey of Northern Ireland's address database for Northern Ireland. + +See also: [PAF](#paf). + +### Points +**Story points.** Units for estimating the relative size or effort of user stories, rather than hours. + +See also: [Planning Poker](#planning-poker), [Velocity](s-z.md#velocity). + +### Polymorphism +The ability of one interface to work with different types, so that the same call does different things depending on the object it is made on. + +See also: [OO](#oo). + +### POP +**Point of Presence.** A location, such as a building or data centre, where a network provider has equipment and where others can connect to its network. + +See also: [ISP](g-k.md#isp). + +### Portability +How easily software can be moved to a different platform or operating system without major rework. + +See also: [POSIX](#posix). + +### POSIX +**Portable Operating System Interface.** IEEE standards that define the API, shell and utilities of Unix-like operating systems, so software can move between them. + +See also: [Unix](s-z.md#unix), [Sh](s-z.md#sh). + +### Postmortem +A review at the end of a project, and its report, in which the team looks at what went well and badly and draws lessons for next time. + +See also: [Milestone Retrospective](l-n.md#milestone-retrospective). + +### POTS +**Plain Old Telephone Service.** Basic analogue voice telephony over a copper line. + +See also: [PSTN](#pstn), [FXS](d-f.md#fxs). + +### PPP +**Point-to-Point Protocol.** A data link protocol for a direct link between two nodes, with authentication, link negotiation and network-layer configuration. Its variants, PPPoE and PPPoA, carry broadband sessions. + +See also: [PPPoE](#pppoe), [CHAP](a-c.md#chap), [PAP](#pap), [L2TP](l-n.md#l2tp). + +### PPPoE +**PPP over Ethernet.** PPP frames carried inside Ethernet frames, so broadband providers can authenticate users and manage sessions over Ethernet-based access networks. + +See also: [PPP](#ppp), [BNG](a-c.md#bng). + +### PPTP +**Point-to-Point Tunnelling Protocol.** An old VPN protocol that tunnels PPP over GRE with a TCP control channel. Its security is broken, so it should not be used. + +See also: [L2TP](l-n.md#l2tp), [IPSec](g-k.md#ipsec). + +### Preemption +Interrupting a running task, without its cooperation, to run another, intending to resume it later. A preemptive scheduler does this, typically to run a higher-priority task. + +See also: [Scheduler](s-z.md#scheduler), [RTOS](#rtos). + +### Preview +A meeting, with material sent out beforehand, to probe a proposed solution and suggest alternatives. Unlike a review, it looks for solutions rather than defects. + +See also: [Engineering Discussion](d-f.md#engineering-discussion), [Review](#review). + +### PRI +**Primary Rate Interface.** ISDN access for larger sites. On an E1 (2.048 Mbit/s) it has 30 bearer channels and one signalling channel; on a T1 (1.544 Mbit/s), 23 bearers and one signalling channel. BT sold it as ISDN30. + +See also: [ISDN](g-k.md#isdn), [BRI](a-c.md#bri), [ISDN30](g-k.md#isdn30), [Q.931](#q931). + +### PRINCE2 +**Projects in Controlled Environments.** A process-based project management method that originated in UK government and is widely used in the UK and Europe. + +See also: [CCTA](a-c.md#ccta). + +### Process +A standard way of doing an activity or task, whether written down or not. A defined process is documented. The word also refers to running the process, as in "the build process". + +See also: [Process Flow](#process-flow), [Engineering Process](d-f.md#engineering-process). + +### Process Flow +A model of a process that defines its steps, events, inputs and outputs. + +See also: [Process](#process). + +### Product Owner +The Scrum role responsible for maximising the value of the product: managing the product backlog and deciding what the team works on next. + +See also: [Scrum](s-z.md#scrum), [Backlog](a-c.md#backlog). + +### Product Release +A release made for distribution or deployment to end users. + +See also: [Release](#release). + +### Programming language +A formal language for writing instructions that a computer can carry out, after compilation or interpretation. + +See also: [Programming paradigm](#programming-paradigm), [Compiled Language](a-c.md#compiled-language), [Interpreted Language](g-k.md#interpreted-language). + +### Programming paradigm +A style of programming, and a way of classifying languages by the features that support it. Examples are imperative, procedural, object-oriented, functional, declarative and logic programming. Most modern languages support several. + +See also: [OO](#oo), [AOP](a-c.md#aop). + +### Progressive Elaboration +Defining a project's requirements and plans in more detail as the project goes on and more becomes known. The term comes from the PMBOK. + +See also: [Rolling Wave Planning](#rolling-wave-planning), [Project Headlights](#project-headlights). + +### Project +A temporary piece of work to create a unique product, service or result. + +See also: [Project Charter](#project-charter), [Project Plan](#project-plan). + +### Project Build +A build made through the project's shared build process, usually in a dedicated build environment. + +See also: [Local Build](l-n.md#local-build), [Build Environment](a-c.md#build-environment). + +### Project Business Manager +**PBM.** The person responsible for a project's business outcome: staffing, resources, people issues and dealing with the client. They make the top-level decisions and usually defer technical ones to the technical leads. + +See also: [Project Manager](#project-manager). + +### Project Charter +The document that starts a project, setting out its objectives, business case, risks, resources and constraints. + +See also: [Project Sponsor](#project-sponsor), [Fuzzy Front End](d-f.md#fuzzy-front-end). + +### Project Chartering +Summarising a project's key success factors on one sheet, often a flip chart on the team room wall. + +See also: [Project Charter](#project-charter). + +### Project Estimate +An estimate for a whole project, or a large part of one, usually using several techniques. + +See also: [Task Estimate](s-z.md#task-estimate), [Estimate](d-f.md#estimate). + +### Project Headlights +The idea that a project can only plan with confidence a limited distance ahead, like driving within the range of a car's headlights. Beyond that, plans are rougher. + +See also: [Rolling Wave Planning](#rolling-wave-planning), [Progressive Elaboration](#progressive-elaboration). + +### Project History +A summary of the significant information and statistics about a whole project. + +See also: [Project Log](#project-log), [Postmortem](#postmortem). + +### Project Log +A record of the significant information and statistics about each phase of a project. + +See also: [Project History](#project-history). + +### Project Management +**PM.** Planning, tracking, controlling and reporting on a project. + +See also: [PRINCE2](#prince2), [Project Management Body of Knowledge](#project-management-body-of-knowledge). + +### Project Management Body of Knowledge +**PMBOK.** The Project Management Institute's guide to the generally recognised knowledge and practices of project management. + +See also: [Project Management Institute](#project-management-institute). + +### Project Management Institute +**PMI.** A professional association for project managers, which publishes the PMBOK and runs certifications. + +See also: [Project Management Body of Knowledge](#project-management-body-of-knowledge). + +### Project Manager +**PM.** The person who manages a project. The role often combines those of the project business manager and the planning and tracking lead. + +See also: [Project Business Manager](#project-business-manager), [Planning and Tracking Lead](#planning-and-tracking-lead). + +### Project Plan +**PP.** The controlling document that defines how a project will be carried out. + +See also: [Project Charter](#project-charter), [Work Plan](s-z.md#work-plan). + +### Project Reviewer +Someone outside a project who reviews or audits it, to check that processes are being followed and risks managed. + +See also: [Audit](a-c.md#audit). + +### Project Sponsor +The person or organisation that sponsors a project: starts it, provides its resources, oversees its manager and makes sure it meets stakeholders' needs. + +See also: [Authority](a-c.md#authority), [Project Charter](#project-charter). + +### Pseudocode +An informal, readable description of an algorithm, written in structured natural language rather than a real programming language. + +### PSTN +**Public Switched Telephone Network.** The world's interconnected circuit-switched telephone networks, fixed and mobile. Its core is now digital, and many countries are moving its services to IP. + +See also: [POTS](#pots), [Circuit Switched](a-c.md#circuit-switched), [SS7](s-z.md#ss7). + +### PTP +**Precision Time Protocol.** The IEEE 1588 protocol for synchronising clocks across a network to sub-microsecond accuracy, with hardware timestamping. Mobile networks, finance and industrial control use it. + +See also: [NTP](l-n.md#ntp), [MRTIE](l-n.md#mrtie). + +### PTT +**Push-to-Talk.** Talking over a half-duplex channel by holding a button to transmit and releasing it to listen, as on a two-way radio. + +See also: [Half Duplex](g-k.md#half-duplex). + +### PVC +**Permanent Virtual Circuit.** A virtual circuit set up permanently between two endpoints, so no call set-up is needed. Frame Relay and ATM services were usually built from PVCs. + +See also: [SVC](s-z.md#svc), [Frame Relay](d-f.md#frame-relay), [ATM](a-c.md#atm). + +### PW +**Pseudowire.** The emulation of a point-to-point circuit, such as Ethernet, TDM or ATM, over a packet network, typically MPLS. + +See also: [VPWS](s-z.md#vpws), [L2VPN](l-n.md#l2vpn). + +### PWFQ +**Priority Weighted Fair Queuing.** A queuing scheme that serves strict-priority queues first and shares the remaining capacity between the other queues by weight. + +See also: [NGWFQ](l-n.md#ngwfq), [QoS](#qos). + +### Python +A high-level, general-purpose language created by Guido van Rossum and first released in 1991. It is known for readable code with significant indentation and a large standard library. Python 2 reached end of life in 2020, and Python 3 is the current version. + +See also: [Interpreted Language](g-k.md#interpreted-language). + +## Q + +### Q.931 {#q931} +The ITU-T ISDN signalling protocol on the D channel, which sets up, maintains and clears calls between the user and the network. H.323 and QSIG reuse its messages. + +See also: [ISDN](g-k.md#isdn), [PRI](#pri), [QSIG](#qsig). + +### QA Lead +**QAL.** The person responsible for the quality of a project's process and product. + +See also: [Quality Assurance](#quality-assurance). + +### QAM +**Quadrature Amplitude Modulation.** Modulation that sends data by varying the amplitude of two carriers 90° apart, so that each symbol carries several bits. Higher orders, such as 256-QAM, carry more bits but need a cleaner signal. DSL, cable, Wi-Fi and mobile networks use it. + +See also: [FSK](d-f.md#fsk), [OFDMA](#ofdma). + +### QoS +**Quality of Service.** The mechanisms that give different traffic different treatment in a network, through classification, marking, queuing and policing. They protect delay-sensitive traffic, such as voice, from loss, delay and jitter. The term also means the measured performance of a service. + +See also: [DSCP](d-f.md#dscp), [CoS](a-c.md#cos), [RSVP](#rsvp), [PWFQ](#pwfq). + +### QSIG +An ISDN-based signalling protocol between PBXs in a private network, standardised by Ecma and ISO. It supports basic calls and supplementary services across different vendors' equipment. + +See also: [DPNSS](d-f.md#dpnss), [Q.931](#q931). + +### Quality +How well a system and its artefacts meet their requirements and standards, and the activities that make sure they do. + +See also: [Quality Assurance](#quality-assurance), [Quality Control](#quality-control). + +### Quality Assurance +**QA.** Activities that prevent defects, by making sure the right processes are in place and followed. + +See also: [Quality Control](#quality-control), [Quality Plan](#quality-plan). + +### Quality Assurance Plan +See [Quality Plan](#quality-plan). + +### Quality Control +**QC.** Activities that find defects, mainly reviews and testing. + +See also: [Quality Assurance](#quality-assurance), [Testing](s-z.md#testing). + +### Quality Plan +**QP.** A plan for the quality methods and practices a project will use, and which artefacts they cover. It often leaves the testing details to the test plan. + +See also: [Test Plan](s-z.md#test-plan). + +### Quick Design Session +A short meeting, often at a whiteboard, where two or more developers settle a design choice that has wide consequences. + +See also: [Simple Design](s-z.md#simple-design). + +## R + +### R Language +A language and free environment for statistical computing and graphics, widely used by statisticians and data scientists. + +See also: [Python](#python). + +### RACI +**Responsible, Accountable, Consulted, Informed.** A responsibility matrix that sets out, for each task or deliverable, who does the work, who is accountable for it, who is consulted and who is kept informed. + +### RAD +**Rapid Application Development.** An approach that develops software quickly through prototypes, workshops, early user testing and component reuse, with less formal documentation. + +See also: [Rapid Application Development](#rapid-application-development), [DSDM](d-f.md#dsdm), [Joint Application Development](g-k.md#joint-application-development). + +### RAD Environment +A development tool that combines a language and an IDE with a toolbox of ready-made user interface components, for building applications quickly. + +See also: [IDE](g-k.md#ide), [RAD](#rad). + +### Radius +**RADIUS: Remote Authentication Dial-In User Service.** The protocol (RFC 2865) that network access servers use to authenticate users, authorise their access and record their usage against a central server. It is widely used for broadband, Wi-Fi and VPN access. + +See also: [NAS](l-n.md#nas), [EAP](d-f.md#eap), [FNA](d-f.md#fna). + +### RAN +**Radio Access Network.** The part of a mobile network between devices and the core: the base stations and their controllers. GERAN, UTRAN and E-UTRAN are the 2G, 3G and 4G versions. + +See also: [GERAN](g-k.md#geran), [UTRAN](s-z.md#utran), [E-UTRAN](d-f.md#e-utran), [Backhaul](a-c.md#backhaul). + +### RANAP +**Radio Access Network Application Part.** The UMTS signalling protocol on the Iu interface between the radio access network (the RNC) and the core (MSC or SGSN). + +See also: [RNC](#rnc), [UTRAN](s-z.md#utran). + +### RANCID +**Really Awesome New Cisco confIg Differ.** An open-source tool that logs in to network devices, collects their configurations, stores them in version control and reports changes. + +### Rapid Application Development +See [RAD](#rad). + +### RARP +**Reverse Address Resolution Protocol.** An obsolete protocol (RFC 903) with which a device that knows only its MAC address asks a server for its IP address. BOOTP and DHCP replaced it. + +See also: [BOOTP](a-c.md#bootp), [DHCP](d-f.md#dhcp). + +### RAS +**Registration, Admission and Status.** The part of H.323 (in H.225) with which endpoints register with a gatekeeper and ask permission to make calls. RAS also stands for remote access server. + +See also: [H.323](g-k.md#h323). + +### RDBMS +**Relational Database Management System.** A database system based on Edgar Codd's relational model, which stores data in tables with rows and columns and is queried with SQL. + +See also: [SQL](s-z.md#sql), [NoSQL](l-n.md#nosql). + +### RDP +**Remote Desktop Protocol.** Microsoft's protocol for using another computer's desktop over a network, on TCP and UDP port 3389. + +### Reading Inspection +An inspection that follows every step of the full process except the inspection meeting. + +See also: [Inspection](g-k.md#inspection). + +### Refactoring +Improving the internal structure of code without changing what it does, in small steps backed by tests. + +See also: [Technical Debt](s-z.md#technical-debt), [TDD](s-z.md#tdd). + +### Regression testing +Re-running tests after a change to check that what worked before still works. + +See also: [Automated Testing](a-c.md#automated-testing). + +### Regular expression +A pattern that describes a set of strings, used to search, match, validate and replace text. It is also called a regex. + +See also: [Sed](s-z.md#sed), [Awk](a-c.md#awk). + +### Relative Estimation +Estimating work by comparing items with each other, or grouping items of similar difficulty, rather than estimating each in absolute units. + +See also: [Points](#points), [T-Shirt Sizing](s-z.md#t-shirt-sizing). + +### Release +Delivering a deployable version of a system to a customer, such as a test group or end users. The word also means the version delivered. + +See also: [Release Management](#release-management), [Product Release](#product-release). + +### Release Management +Identifying, packaging and delivering the parts of a product to its customers, internal or external. + +See also: [Release](#release), [Semantic Versioning](s-z.md#semantic-versioning). + +### Release Test +A test that checks software is ready for release. + +### Requirement +A statement of something a system must do, or a quality it must have. + +See also: [Functional Requirement](d-f.md#functional-requirement), [Non-functional Requirement](l-n.md#non-functional-requirement). + +### Requirements +The work of finding out, recording and managing what a software system should do. + +See also: [Requirement](#requirement), [Software Requirements Specification](s-z.md#software-requirements-specification). + +### Requirements Lead +The person responsible for defining, maintaining and tracing a product's requirements, and for the user documentation that follows from them. + +### REST +**Representational State Transfer.** An architecture style for web services in which resources are identified by URLs and handled through a uniform set of stateless operations, usually the HTTP methods. `GET` reads, `POST` creates, `PUT` replaces and `DELETE` removes. + +See also: [HTTP](g-k.md#http), [SOAP](s-z.md#soap), [API](a-c.md#api). + +### Review +A defined process in which people other than an artefact's author examine it to find issues. Reviews range from informal desk checks to formal inspections. + +See also: [Inspection](g-k.md#inspection), [Desk Check](d-f.md#desk-check), [Walkthrough](s-z.md#walkthrough). + +### Reviewer +A person who takes part in a review. + +See also: [Review](#review). + +### Revision +One recorded version of an artefact, usually as numbered by a version control system. + +See also: [Version Control](s-z.md#version-control). + +### Revision Control +See [Version Control](s-z.md#version-control). + +### Rework +Unplanned work needed to bring an artefact into line with the project's needs, such as fixing defects. + +See also: [Update](s-z.md#update). + +### RFC +**Request for Comments.** The IETF's numbered document series, which includes the internet's standards and many informational and experimental documents. + +See also: [IETF](g-k.md#ietf). + +### RIP +**Routing Information Protocol.** One of the oldest distance-vector routing protocols. It uses hop count as its metric, with a limit of 15 hops, so it suits only small networks. + +See also: [OSPF](#ospf), [IGRP](g-k.md#igrp), [IGP](g-k.md#igp). + +### Risk +A possible future event that would harm a project's features, budget, schedule or quality if it happened. + +See also: [Risk Management](#risk-management), [Risk List](#risk-list). + +### Risk Analysis +Assessing each risk for its likelihood and impact. + +See also: [Risk Management](#risk-management). + +### Risk Identification +Finding and recording a project's current risks. + +See also: [Risk Management](#risk-management). + +### Risk List +A list of a project's current and past risks, with their analysis and mitigation plans. + +See also: [Risk Management](#risk-management), [Extrinsic Risk Management](d-f.md#extrinsic-risk-management). + +### Risk Management +Identifying, analysing and controlling a project's risks, either explicitly or as part of how the project is run. + +See also: [Risk](#risk), [Extrinsic Risk Management](d-f.md#extrinsic-risk-management), [Intrinsic Risk Management](g-k.md#intrinsic-risk-management), [Risk Mitigation](#risk-mitigation). + +### Risk Mitigation +Planning and taking action to reduce a risk's likelihood or impact. + +See also: [Risk Management](#risk-management). + +### Risk Reward Matrix +A two-by-two grid for comparing options, with risk on one axis and reward on the other. High-reward, low-risk options are the best candidates; high-risk, low-reward ones are to be avoided. The size of each marker can show the resources each option needs. + +### RNC +**Radio Network Controller.** The UMTS node that controls a group of Node Bs. It manages radio resources and handovers, and ciphers user data. It connects to the circuit-switched core through the Iu-CS interface and to the packet core through Iu-PS. + +See also: [Node B](l-n.md#node-b), [UTRAN](s-z.md#utran), [RANAP](#ranap), [BSC](a-c.md#bsc). + +### RNSAP +**Radio Network Subsystem Application Part.** The UMTS signalling protocol between RNCs, on the Iur interface, used for soft handover and moving a connection from one RNC to another. + +See also: [RNC](#rnc), [UTRAN](s-z.md#utran). + +### Role-feature-reason +The usual template for writing user stories: "As a *role*, I want *feature*, so that *reason*." + +See also: [User Stories](s-z.md#user-stories). + +### Rolling Wave Planning +Planning the near future in detail and later work only roughly, then adding detail as each period comes closer. + +See also: [Project Headlights](#project-headlights), [Progressive Elaboration](#progressive-elaboration). + +### Root of Trust +**RoT.** The hardware, firmware and keys that a device trusts without checking, because everything else is checked against them. It anchors secure boot, device identity and key storage, and is usually built into the chip or a secure element. + +See also: [RoT](#rot), [Secure Element](s-z.md#secure-element), [TrustZone](s-z.md#trustzone). + +### RoT +See [Root of Trust](#root-of-trust). + +### Round Robin +A scheduling method that gives each task or queue a turn in a fixed circular order, with equal time slices and no priorities. It is simple and no task is starved. + +See also: [Scheduler](s-z.md#scheduler), [Preemption](#preemption). + +### Router +A device that forwards packets between networks, choosing the next hop for each from its routing table, which it builds from configuration and routing protocols. + +See also: [Switch](s-z.md#switch), [Control Plane](a-c.md#control-plane), [BGP](a-c.md#bgp), [OSPF](#ospf). + +### RPC +**Remote Procedure Call.** Calling a procedure that runs in another process or on another machine as if it were a local call, with the messaging hidden by the framework. + +See also: [JSON-RPC](g-k.md#json-rpc), [XML-RPC](s-z.md#xml-rpc), [SOAP](s-z.md#soap). + +### RRC +**Radio Resource Control.** The 3GPP control protocol between a device and the radio network in UMTS, LTE and 5G. It sets up and releases connections and radio bearers, broadcasts system information and manages mobility. A state machine, with idle and connected states, governs the device. + +See also: [PDCP](#pdcp), [E-UTRAN](d-f.md#e-utran). + +### RSTP +**Rapid Spanning Tree Protocol.** IEEE 802.1w, a faster version of the spanning tree protocol that recovers from a topology change in seconds rather than tens of seconds. It is now part of 802.1D. + +See also: [STP](s-z.md#stp). + +### RSVP +**Resource Reservation Protocol.** A protocol (RFC 2205) with which receivers reserve network resources for a flow along its path. Its extension, RSVP-TE, sets up traffic-engineered MPLS paths. + +See also: [QoS](#qos), [LSP](l-n.md#lsp). + +### RTCP +**RTP Control Protocol.** The companion to RTP, defined in RFC 3550. It reports statistics on an RTP session, such as packet loss, jitter and round-trip time, and helps synchronise streams. + +See also: [RTP](#rtp). + +### RTOS +**Real-Time Operating System.** An operating system that guarantees tasks respond within defined time limits, usually by priority-based preemptive scheduling. FreeRTOS, Zephyr and VxWorks are examples. + +See also: [Scheduler](s-z.md#scheduler), [Preemption](#preemption), [MCU](l-n.md#mcu). + +### RTP +**Real-time Transport Protocol.** The protocol (RFC 3550) that carries audio and video over IP, usually on UDP, with sequence numbers and timestamps so receivers can play media out smoothly. SIP or another protocol sets up the session. + +See also: [RTCP](#rtcp), [SIP](s-z.md#sip), [VoIP](s-z.md#voip). + +### RTSP +**Real Time Streaming Protocol.** A protocol for controlling streaming media servers with commands such as play, pause and record. The media itself usually travels over RTP. + +See also: [RTP](#rtp). + +### Ruby +A dynamic, object-oriented scripting language created by Yukihiro Matsumoto in the mid-1990s, designed to make programmers productive and happy. + +See also: [Ruby on Rails](#ruby-on-rails). + +### Ruby on Rails +A web application framework written in Ruby, built on the model-view-controller pattern and known for "convention over configuration". + +See also: [Ruby](#ruby). + +### Rule of Simplicity +Kent Beck's rules, in priority order, for judging whether code is simple enough: it passes the tests, reveals its intent, has no duplication and has the fewest elements. + +See also: [Simple Design](s-z.md#simple-design), [KISS Principle](g-k.md#kiss-principle). + +### RUP +**Rational Unified Process.** An iterative software development process framework from Rational Software (later IBM), with four phases: inception, elaboration, construction and transition. + +See also: [UML](s-z.md#uml), [Iterative Development](g-k.md#iterative-development). diff --git a/content/glossary/redirects.tsv b/content/glossary/redirects.tsv new file mode 100644 index 0000000..b3eccca --- /dev/null +++ b/content/glossary/redirects.tsv @@ -0,0 +1,1140 @@ +# Old glossary URLs and where they now point. redirect_from and redirect_to are in the form +# mkdocs-redirects takes for redirect_maps (pages relative to docs/), for the tarf.co.uk rows. +old_url redirect_from redirect_to note +https://tarf.co.uk/Glossary/ Glossary/index.md glossary/index.md +https://tarf.co.uk/Glossary/1/1/ Glossary/1/1.md glossary/s-z.md letter index +https://tarf.co.uk/Glossary/1/100%20Mbps---Fast%20Ethernet/ Glossary/1/100 Mbps---Fast Ethernet.md glossary/s-z.md#100-mbps-fast-ethernet renamed to "100 Mbps (Fast Ethernet)" +https://tarf.co.uk/Glossary/5/5/ Glossary/5/5.md glossary/s-z.md letter index +https://tarf.co.uk/Glossary/5/5ESS/ Glossary/5/5ESS.md glossary/s-z.md#5ess +https://tarf.co.uk/Glossary/5/5G/ Glossary/5/5G.md 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+https://tarf.co.uk/Glossary/c/CCITT/ Glossary/c/CCITT.md glossary/a-c.md#ccitt +https://tarf.co.uk/Glossary/c/CCS/ Glossary/c/CCS.md glossary/a-c.md#ccs +https://tarf.co.uk/Glossary/c/CCTA/ Glossary/c/CCTA.md glossary/a-c.md#ccta +https://tarf.co.uk/Glossary/c/CDMA/ Glossary/c/CDMA.md glossary/a-c.md#cdma +https://tarf.co.uk/Glossary/c/CDMA2000/ Glossary/c/CDMA2000.md glossary/a-c.md#cdma2000 +https://tarf.co.uk/Glossary/c/CDR/ Glossary/c/CDR.md glossary/a-c.md#cdr +https://tarf.co.uk/Glossary/c/CE/ Glossary/c/CE.md glossary/a-c.md#ce +https://tarf.co.uk/Glossary/c/CER/ Glossary/c/CER.md glossary/a-c.md#cer +https://tarf.co.uk/Glossary/c/Ceremonies/ Glossary/c/Ceremonies.md glossary/a-c.md#ceremonies +https://tarf.co.uk/Glossary/c/CESG/ Glossary/c/CESG.md glossary/a-c.md#cesg +https://tarf.co.uk/Glossary/c/CFi/ Glossary/c/CFi.md glossary/a-c.md#cfi +https://tarf.co.uk/Glossary/c/CGI/ Glossary/c/CGI.md glossary/a-c.md#cgi +https://tarf.co.uk/Glossary/c/Change%20Control%20Board/ Glossary/c/Change Control Board.md glossary/a-c.md#change-control-board +https://tarf.co.uk/Glossary/c/Change%20Control%20Plan/ Glossary/c/Change Control Plan.md glossary/a-c.md#change-control-plan +https://tarf.co.uk/Glossary/c/Change%20Control/ Glossary/c/Change Control.md glossary/a-c.md#change-control +https://tarf.co.uk/Glossary/c/Change%20Management/ Glossary/c/Change Management.md glossary/a-c.md#change-management +https://tarf.co.uk/Glossary/c/Change%20Request/ Glossary/c/Change Request.md glossary/a-c.md#change-request +https://tarf.co.uk/Glossary/c/CHAP/ Glossary/c/CHAP.md glossary/a-c.md#chap +https://tarf.co.uk/Glossary/c/Chrome%20OS/ Glossary/c/Chrome OS.md glossary/a-c.md#chrome-os +https://tarf.co.uk/Glossary/c/Circuit%20Switched/ Glossary/c/Circuit Switched.md glossary/a-c.md#circuit-switched +https://tarf.co.uk/Glossary/c/Class%204%20Softswitch/ Glossary/c/Class 4 Softswitch.md glossary/a-c.md#class-4-softswitch +https://tarf.co.uk/Glossary/c/Class%205%20Softswitch/ Glossary/c/Class 5 Softswitch.md glossary/a-c.md#class-5-softswitch +https://tarf.co.uk/Glossary/c/Class%20Model/ Glossary/c/Class Model.md glossary/a-c.md#class-model +https://tarf.co.uk/Glossary/c/CLF/ Glossary/c/CLF.md glossary/a-c.md#clf +https://tarf.co.uk/Glossary/c/CMDB/ Glossary/c/CMDB.md glossary/a-c.md#cmdb +https://tarf.co.uk/Glossary/c/CNG/ Glossary/c/CNG.md glossary/a-c.md#cng +https://tarf.co.uk/Glossary/c/Cobol/ Glossary/c/Cobol.md glossary/a-c.md#cobol +https://tarf.co.uk/Glossary/c/Code%20and%20Fix%20Lifecycle/ Glossary/c/Code and Fix Lifecycle.md glossary/a-c.md#code-and-fix-lifecycle +https://tarf.co.uk/Glossary/c/Codecs/ Glossary/c/Codecs.md glossary/a-c.md#codecs +https://tarf.co.uk/Glossary/c/Coding%20Standard/ Glossary/c/Coding Standard.md glossary/a-c.md#coding-standard +https://tarf.co.uk/Glossary/c/Coding/ Glossary/c/Coding.md glossary/a-c.md#coding +https://tarf.co.uk/Glossary/c/CoE/ Glossary/c/CoE.md glossary/a-c.md#coe +https://tarf.co.uk/Glossary/c/COFDM/ Glossary/c/COFDM.md glossary/a-c.md#cofdm +https://tarf.co.uk/Glossary/c/Collaboration%20Model/ Glossary/c/Collaboration Model.md glossary/a-c.md#collaboration-model +https://tarf.co.uk/Glossary/c/Collaborative%20Construction/ Glossary/c/Collaborative Construction.md glossary/a-c.md#collaborative-construction +https://tarf.co.uk/Glossary/c/Collective%20code%20ownership/ Glossary/c/Collective code ownership.md glossary/a-c.md#collective-code-ownership +https://tarf.co.uk/Glossary/c/COLO/ Glossary/c/COLO.md glossary/a-c.md#colo +https://tarf.co.uk/Glossary/c/Compatibility%20Test/ Glossary/c/Compatibility Test.md glossary/a-c.md#compatibility-test +https://tarf.co.uk/Glossary/c/Compiled%20Language/ Glossary/c/Compiled Language.md glossary/a-c.md#compiled-language +https://tarf.co.uk/Glossary/c/Compiler%20Back%20end/ Glossary/c/Compiler Back end.md glossary/a-c.md#compiler-back-end +https://tarf.co.uk/Glossary/c/Compiler%20Front%20end/ Glossary/c/Compiler Front end.md glossary/a-c.md#compiler-front-end +https://tarf.co.uk/Glossary/c/Compiler%20Middle%20end/ Glossary/c/Compiler Middle end.md glossary/a-c.md#compiler-middle-end +https://tarf.co.uk/Glossary/c/Compiler%20preprocessor/ Glossary/c/Compiler preprocessor.md glossary/a-c.md#compiler-preprocessor +https://tarf.co.uk/Glossary/c/Complier/ Glossary/c/Complier.md glossary/a-c.md#compiler renamed to "Compiler" +https://tarf.co.uk/Glossary/c/Component%20Test/ Glossary/c/Component Test.md glossary/a-c.md#component-test +https://tarf.co.uk/Glossary/c/Component/ Glossary/c/Component.md glossary/a-c.md#component +https://tarf.co.uk/Glossary/c/Cone%20of%20Uncertainty/ Glossary/c/Cone of Uncertainty.md glossary/a-c.md#cone-of-uncertainty +https://tarf.co.uk/Glossary/c/Configuration%20Item/ Glossary/c/Configuration Item.md glossary/a-c.md#configuration-item +https://tarf.co.uk/Glossary/c/Configuration%20Management/ Glossary/c/Configuration Management.md glossary/a-c.md#configuration-management +https://tarf.co.uk/Glossary/c/Configuration%20Test/ Glossary/c/Configuration Test.md glossary/a-c.md#configuration-test +https://tarf.co.uk/Glossary/c/Construction%20Environment/ Glossary/c/Construction Environment.md glossary/a-c.md#construction-environment +https://tarf.co.uk/Glossary/c/Construction%20Lead/ Glossary/c/Construction Lead.md glossary/a-c.md#construction-lead +https://tarf.co.uk/Glossary/c/Construction%20Standard/ Glossary/c/Construction Standard.md glossary/a-c.md#construction-standard +https://tarf.co.uk/Glossary/c/Construction%20Test%20Environment/ Glossary/c/Construction Test Environment.md glossary/a-c.md#construction-test-environment +https://tarf.co.uk/Glossary/c/Construction%20Testing/ Glossary/c/Construction Testing.md glossary/a-c.md#construction-testing +https://tarf.co.uk/Glossary/c/Construction/ Glossary/c/Construction.md glossary/a-c.md#construction +https://tarf.co.uk/Glossary/c/Construx%20Knowledge%20Area/ Glossary/c/Construx Knowledge Area.md glossary/s-z.md#software-engineering-body-of-knowledge renamed to "Software Engineering Body of Knowledge" +https://tarf.co.uk/Glossary/c/Continuous%20Deployment/ Glossary/c/Continuous Deployment.md glossary/a-c.md#continuous-deployment +https://tarf.co.uk/Glossary/c/continuous%20integration/ Glossary/c/continuous integration.md glossary/a-c.md#continuous-integration +https://tarf.co.uk/Glossary/c/Control%20Plane/ Glossary/c/Control Plane.md glossary/a-c.md#control-plane +https://tarf.co.uk/Glossary/c/Copyleft/ Glossary/c/Copyleft.md glossary/a-c.md#copyleft +https://tarf.co.uk/Glossary/c/Corrective%20Activity%20Management/ Glossary/c/Corrective Activity Management.md glossary/a-c.md dropped +https://tarf.co.uk/Glossary/c/CoS/ Glossary/c/CoS.md glossary/a-c.md#cos +https://tarf.co.uk/Glossary/c/COTS/ Glossary/c/COTS.md glossary/a-c.md#cots +https://tarf.co.uk/Glossary/c/CPE/ Glossary/c/CPE.md glossary/a-c.md#cpe +https://tarf.co.uk/Glossary/c/CPM/ Glossary/c/CPM.md glossary/a-c.md#cpm +https://tarf.co.uk/Glossary/c/CPS/ Glossary/c/CPS.md glossary/a-c.md#cps +https://tarf.co.uk/Glossary/c/CRC%20Cards/ Glossary/c/CRC Cards.md glossary/a-c.md#crc-cards +https://tarf.co.uk/Glossary/c/CRC/ Glossary/c/CRC.md glossary/a-c.md#crc +https://tarf.co.uk/Glossary/c/CSCF/ Glossary/c/CSCF.md glossary/a-c.md#cscf +https://tarf.co.uk/Glossary/c/csh/ Glossary/c/csh.md glossary/a-c.md#csh +https://tarf.co.uk/Glossary/c/Csharp/ Glossary/c/Csharp.md glossary/a-c.md#c_2 renamed to "C#" +https://tarf.co.uk/Glossary/c/CSI/ Glossary/c/CSI.md glossary/a-c.md#csi +https://tarf.co.uk/Glossary/c/CSMA/ Glossary/c/CSMA.md glossary/a-c.md#csma +https://tarf.co.uk/Glossary/c/CSS/ Glossary/c/CSS.md glossary/a-c.md#css +https://tarf.co.uk/Glossary/c/CUE%20/ Glossary/c/CUE .md glossary/a-c.md#cue +https://tarf.co.uk/Glossary/c/Customer%20Development/ Glossary/c/Customer Development.md glossary/a-c.md#customer-development +https://tarf.co.uk/Glossary/c/CVSD/ Glossary/c/CVSD.md glossary/a-c.md#cvsd +https://tarf.co.uk/Glossary/d/d/ Glossary/d/d.md glossary/d-f.md letter index +https://tarf.co.uk/Glossary/d/DAD/ Glossary/d/DAD.md glossary/d-f.md#dad +https://tarf.co.uk/Glossary/d/Daily%20Meeting/ Glossary/d/Daily Meeting.md glossary/d-f.md#daily-meeting +https://tarf.co.uk/Glossary/d/Daily%20Scrum/ Glossary/d/Daily Scrum.md glossary/d-f.md#daily-scrum +https://tarf.co.uk/Glossary/d/Dark%20Fibre/ Glossary/d/Dark Fibre.md glossary/d-f.md#dark-fibre +https://tarf.co.uk/Glossary/d/DASS1/ Glossary/d/DASS1.md glossary/d-f.md#dass1 +https://tarf.co.uk/Glossary/d/DASS2/ Glossary/d/DASS2.md glossary/d-f.md#dass2 +https://tarf.co.uk/Glossary/d/data%20modeling/ Glossary/d/data modeling.md glossary/d-f.md#data-modelling renamed to "Data modelling" +https://tarf.co.uk/Glossary/d/Data%20Plane/ Glossary/d/Data Plane.md glossary/d-f.md#data-plane +https://tarf.co.uk/Glossary/d/Database%20Lead/ Glossary/d/Database Lead.md glossary/d-f.md#database-lead +https://tarf.co.uk/Glossary/d/Date%20Warehouse/ Glossary/d/Date Warehouse.md glossary/d-f.md#data-warehouse renamed to "Data Warehouse" +https://tarf.co.uk/Glossary/d/DCE/ Glossary/d/DCE.md glossary/d-f.md#dce +https://tarf.co.uk/Glossary/d/DDK/ Glossary/d/DDK.md glossary/d-f.md#ddk +https://tarf.co.uk/Glossary/d/DDOS/ Glossary/d/DDOS.md glossary/d-f.md#ddos +https://tarf.co.uk/Glossary/d/Decomposition%20Estimation/ Glossary/d/Decomposition Estimation.md glossary/d-f.md#decomposition-estimation +https://tarf.co.uk/Glossary/d/Defect%20Management/ Glossary/d/Defect Management.md glossary/d-f.md#defect-management +https://tarf.co.uk/Glossary/d/Defect%20Report/ Glossary/d/Defect Report.md glossary/d-f.md#defect-report +https://tarf.co.uk/Glossary/d/Defect/ Glossary/d/Defect.md glossary/d-f.md#defect +https://tarf.co.uk/Glossary/d/Definition%20of%20Done/ Glossary/d/Definition of Done.md glossary/d-f.md#definition-of-done +https://tarf.co.uk/Glossary/d/Definition%20of%20Ready/ Glossary/d/Definition of Ready.md glossary/d-f.md#definition-of-ready +https://tarf.co.uk/Glossary/d/Deliverable/ Glossary/d/Deliverable.md glossary/d-f.md#deliverable +https://tarf.co.uk/Glossary/d/Deplhi/ Glossary/d/Deplhi.md glossary/d-f.md#delphi renamed to "Delphi" +https://tarf.co.uk/Glossary/d/Deployment%20Lead/ Glossary/d/Deployment Lead.md glossary/d-f.md#deployment-lead +https://tarf.co.uk/Glossary/d/Deployment%20Plan/ Glossary/d/Deployment Plan.md glossary/d-f.md#deployment-plan +https://tarf.co.uk/Glossary/d/Deployment/ Glossary/d/Deployment.md glossary/d-f.md#deployment +https://tarf.co.uk/Glossary/d/DER/ Glossary/d/DER.md glossary/d-f.md#der +https://tarf.co.uk/Glossary/d/DES/ Glossary/d/DES.md glossary/d-f.md#des +https://tarf.co.uk/Glossary/d/Design%20Lead/ Glossary/d/Design Lead.md glossary/d-f.md#design-lead +https://tarf.co.uk/Glossary/d/Design%20Pattern/ Glossary/d/Design Pattern.md glossary/d-f.md#design-pattern +https://tarf.co.uk/Glossary/d/Design%20to%20Tools/ Glossary/d/Design to Tools.md glossary/d-f.md#design-to-tools +https://tarf.co.uk/Glossary/d/Design/ Glossary/d/Design.md glossary/d-f.md#design +https://tarf.co.uk/Glossary/d/Desk%20Check/ Glossary/d/Desk Check.md glossary/d-f.md#desk-check +https://tarf.co.uk/Glossary/d/Detailed%20Design/ Glossary/d/Detailed Design.md glossary/d-f.md#detailed-design +https://tarf.co.uk/Glossary/d/Detailed%20Schedule/ Glossary/d/Detailed Schedule.md glossary/d-f.md#detailed-schedule +https://tarf.co.uk/Glossary/d/Developer%20Integration%20Test/ Glossary/d/Developer Integration Test.md glossary/d-f.md#developer-integration-test +https://tarf.co.uk/Glossary/d/Developer/ Glossary/d/Developer.md glossary/d-f.md#developer +https://tarf.co.uk/Glossary/d/development%20environment/ Glossary/d/development environment.md glossary/d-f.md#development-environment +https://tarf.co.uk/Glossary/d/development%20process/ Glossary/d/development process.md glossary/d-f.md#development-process +https://tarf.co.uk/Glossary/d/DevOps/ Glossary/d/DevOps.md glossary/d-f.md#devops +https://tarf.co.uk/Glossary/d/DHCP/ Glossary/d/DHCP.md glossary/d-f.md#dhcp +https://tarf.co.uk/Glossary/d/Diagram/ Glossary/d/Diagram.md glossary/d-f.md#diagram +https://tarf.co.uk/Glossary/d/DLE/ Glossary/d/DLE.md glossary/d-f.md#dle +https://tarf.co.uk/Glossary/d/DLP/ Glossary/d/DLP.md glossary/d-f.md#dlp +https://tarf.co.uk/Glossary/d/DMZ/ Glossary/d/DMZ.md glossary/d-f.md#dmz +https://tarf.co.uk/Glossary/d/DN/ Glossary/d/DN.md glossary/d-f.md#dn +https://tarf.co.uk/Glossary/d/DNB/ Glossary/d/DNB.md glossary/d-f.md#dnb +https://tarf.co.uk/Glossary/d/DNS%20-%20A/ Glossary/d/DNS - A.md glossary/d-f.md#dns-a +https://tarf.co.uk/Glossary/d/DNS%20-%20AAAA/ Glossary/d/DNS - AAAA.md glossary/d-f.md#dns-aaaa +https://tarf.co.uk/Glossary/d/DNS%20-%20CNAME/ Glossary/d/DNS - CNAME.md glossary/d-f.md#dns-cname +https://tarf.co.uk/Glossary/d/DNS%20-%20DNAME/ Glossary/d/DNS - DNAME.md glossary/d-f.md#dns-dname +https://tarf.co.uk/Glossary/d/DNS%20-%20SRV/ Glossary/d/DNS - SRV.md glossary/d-f.md#dns-srv +https://tarf.co.uk/Glossary/d/DNS%20-%20TXT/ Glossary/d/DNS - TXT.md glossary/d-f.md#dns-txt +https://tarf.co.uk/Glossary/d/DNS%20Spoofing/ Glossary/d/DNS Spoofing.md glossary/d-f.md#dns-spoofing +https://tarf.co.uk/Glossary/d/DNS/ Glossary/d/DNS.md glossary/d-f.md#dns +https://tarf.co.uk/Glossary/d/Docker/ Glossary/d/Docker.md glossary/d-f.md#docker +https://tarf.co.uk/Glossary/d/Document%20Collaboration/ Glossary/d/Document Collaboration.md glossary/d-f.md#document-collaboration +https://tarf.co.uk/Glossary/d/Domain%20Name/ Glossary/d/Domain Name.md glossary/d-f.md#domain-name +https://tarf.co.uk/Glossary/d/Dot1Q%20trunking/ Glossary/d/Dot1Q trunking.md glossary/d-f.md#dot1q-trunking +https://tarf.co.uk/Glossary/d/Dot1Q/ Glossary/d/Dot1Q.md glossary/d-f.md#dot1q +https://tarf.co.uk/Glossary/d/dotNET/ Glossary/d/dotNET.md glossary/s-z.md#net renamed to ".NET" +https://tarf.co.uk/Glossary/d/Downstream/ Glossary/d/Downstream.md glossary/d-f.md#downstream +https://tarf.co.uk/Glossary/d/DP/ Glossary/d/DP.md glossary/d-f.md#dp +https://tarf.co.uk/Glossary/d/DPI/ Glossary/d/DPI.md glossary/d-f.md#dpi +https://tarf.co.uk/Glossary/d/DPNSS/ Glossary/d/DPNSS.md glossary/d-f.md#dpnss +https://tarf.co.uk/Glossary/d/DQ/ Glossary/d/DQ.md glossary/d-f.md#dq +https://tarf.co.uk/Glossary/d/Draft/ Glossary/d/Draft.md glossary/d-f.md#draft +https://tarf.co.uk/Glossary/d/driver/ Glossary/d/driver.md glossary/d-f.md#driver +https://tarf.co.uk/Glossary/d/DSCP/ Glossary/d/DSCP.md glossary/d-f.md#dscp +https://tarf.co.uk/Glossary/d/DSDM/ Glossary/d/DSDM.md glossary/d-f.md#dsdm +https://tarf.co.uk/Glossary/d/DSL/ Glossary/d/DSL.md glossary/d-f.md#dsl +https://tarf.co.uk/Glossary/d/DSLAM/ Glossary/d/DSLAM.md glossary/d-f.md#dslam +https://tarf.co.uk/Glossary/d/DTE/ Glossary/d/DTE.md glossary/d-f.md#dte +https://tarf.co.uk/Glossary/d/DTMF/ Glossary/d/DTMF.md glossary/d-f.md#dtmf +https://tarf.co.uk/Glossary/d/DTT/ Glossary/d/DTT.md glossary/d-f.md#dtt +https://tarf.co.uk/Glossary/d/DTV/ Glossary/d/DTV.md glossary/d-f.md#dtv +https://tarf.co.uk/Glossary/d/Duplex/ Glossary/d/Duplex.md glossary/d-f.md#duplex +https://tarf.co.uk/Glossary/d/DVSR/ Glossary/d/DVSR.md glossary/d-f.md#dvsr +https://tarf.co.uk/Glossary/e/E%20NodeB/ Glossary/e/E NodeB.md glossary/d-f.md#e-nodeb +https://tarf.co.uk/Glossary/e/E-UTRAN/ Glossary/e/E-UTRAN.md glossary/d-f.md#e-utran +https://tarf.co.uk/Glossary/e/E.164/ Glossary/e/E.164.md glossary/d-f.md#e164 +https://tarf.co.uk/Glossary/e/e/ Glossary/e/e.md glossary/d-f.md letter index +https://tarf.co.uk/Glossary/e/EAD/ Glossary/e/EAD.md glossary/d-f.md#ead +https://tarf.co.uk/Glossary/e/EAP/ Glossary/e/EAP.md glossary/d-f.md#eap +https://tarf.co.uk/Glossary/e/Earned%20Value%20Management/ Glossary/e/Earned Value Management.md glossary/d-f.md#earned-value-management +https://tarf.co.uk/Glossary/e/Earned%20Value/ Glossary/e/Earned Value.md glossary/d-f.md#earned-value +https://tarf.co.uk/Glossary/e/Echo%20Cancellation%20-%20G.168/ Glossary/e/Echo Cancellation - G.168.md glossary/d-f.md#echo-cancellation-g168 +https://tarf.co.uk/Glossary/e/Echo%20cancellation/ Glossary/e/Echo cancellation.md glossary/d-f.md#echo-cancellation +https://tarf.co.uk/Glossary/e/Echo/ Glossary/e/Echo.md glossary/d-f.md#echo +https://tarf.co.uk/Glossary/e/EDB/ Glossary/e/EDB.md glossary/d-f.md#edb +https://tarf.co.uk/Glossary/e/EDGE/ Glossary/e/EDGE.md glossary/d-f.md#edge +https://tarf.co.uk/Glossary/e/Editor/ Glossary/e/Editor.md glossary/d-f.md#editor +https://tarf.co.uk/Glossary/e/EEE%20802.1Qay/ Glossary/e/EEE 802.1Qay.md glossary/g-k.md#ieee-8021qay renamed to "IEEE 802.1Qay" +https://tarf.co.uk/Glossary/e/EFM/ Glossary/e/EFM.md glossary/d-f.md#efm +https://tarf.co.uk/Glossary/e/Egress/ Glossary/e/Egress.md glossary/d-f.md#egress +https://tarf.co.uk/Glossary/e/EIA/ Glossary/e/EIA.md glossary/d-f.md#eia +https://tarf.co.uk/Glossary/e/EIGRP/ Glossary/e/EIGRP.md glossary/d-f.md#eigrp +https://tarf.co.uk/Glossary/e/embedded%20systems%20programming/ Glossary/e/embedded systems programming.md glossary/d-f.md#embedded-systems-programming +https://tarf.co.uk/Glossary/e/Engineering%20Discussion/ Glossary/e/Engineering Discussion.md glossary/d-f.md#engineering-discussion +https://tarf.co.uk/Glossary/e/Engineering%20Management/ Glossary/e/Engineering Management.md glossary/d-f.md#engineering-management +https://tarf.co.uk/Glossary/e/Engineering%20Process/ Glossary/e/Engineering Process.md glossary/d-f.md#engineering-process +https://tarf.co.uk/Glossary/e/EoFTTC/ Glossary/e/EoFTTC.md glossary/d-f.md#eofttc +https://tarf.co.uk/Glossary/e/EoS/ Glossary/e/EoS.md glossary/d-f.md#eos +https://tarf.co.uk/Glossary/e/ePDG/ Glossary/e/ePDG.md glossary/d-f.md#epdg +https://tarf.co.uk/Glossary/e/Epic/ Glossary/e/Epic.md glossary/d-f.md#epic +https://tarf.co.uk/Glossary/e/EPWS/ Glossary/e/EPWS.md glossary/d-f.md#epws +https://tarf.co.uk/Glossary/e/ESB/ Glossary/e/ESB.md glossary/d-f.md#esb +https://tarf.co.uk/Glossary/e/Estimate/ Glossary/e/Estimate.md glossary/d-f.md#estimate +https://tarf.co.uk/Glossary/e/Estimation/ Glossary/e/Estimation.md glossary/d-f.md#estimation +https://tarf.co.uk/Glossary/e/Ethernet%20over%20twisted%20pair/ Glossary/e/Ethernet over twisted pair.md glossary/d-f.md#ethernet-over-twisted-pair +https://tarf.co.uk/Glossary/e/Ethical%20Hacking/ Glossary/e/Ethical Hacking.md glossary/d-f.md#ethical-hacking +https://tarf.co.uk/Glossary/e/ETL/ Glossary/e/ETL.md glossary/d-f.md#etl +https://tarf.co.uk/Glossary/e/ETSI/ Glossary/e/ETSI.md glossary/d-f.md#etsi +https://tarf.co.uk/Glossary/e/Evaluation/ Glossary/e/Evaluation.md glossary/d-f.md dropped +https://tarf.co.uk/Glossary/e/EVC/ Glossary/e/EVC.md glossary/d-f.md#evc +https://tarf.co.uk/Glossary/e/Evolutionary%20Delivery%20Lifecycle/ Glossary/e/Evolutionary Delivery Lifecycle.md glossary/d-f.md#evolutionary-delivery-lifecycle +https://tarf.co.uk/Glossary/e/Evolutionary%20Prototyping%20Lifecycle/ Glossary/e/Evolutionary Prototyping Lifecycle.md glossary/d-f.md#evolutionary-prototyping-lifecycle +https://tarf.co.uk/Glossary/e/EVPL/ Glossary/e/EVPL.md glossary/d-f.md#evpl +https://tarf.co.uk/Glossary/e/Expert%20Judgment/ Glossary/e/Expert Judgment.md glossary/d-f.md#expert-judgement renamed to "Expert Judgement" +https://tarf.co.uk/Glossary/e/Explicit%20Change%20Control/ Glossary/e/Explicit Change Control.md glossary/d-f.md#explicit-change-control +https://tarf.co.uk/Glossary/e/Explicit%20Risk%20Management/ Glossary/e/Explicit Risk Management.md glossary/d-f.md#explicit-risk-management +https://tarf.co.uk/Glossary/e/Exploratory%20Testing/ Glossary/e/Exploratory Testing.md glossary/d-f.md#exploratory-testing +https://tarf.co.uk/Glossary/e/Extrinsic%20Risk%20Management/ Glossary/e/Extrinsic Risk Management.md glossary/d-f.md#extrinsic-risk-management +https://tarf.co.uk/Glossary/f/f/ Glossary/f/f.md glossary/d-f.md letter index +https://tarf.co.uk/Glossary/f/Facilitation/ Glossary/f/Facilitation.md glossary/d-f.md#facilitation +https://tarf.co.uk/Glossary/f/FCS/ Glossary/f/FCS.md glossary/d-f.md#fcs +https://tarf.co.uk/Glossary/f/FDDI/ Glossary/f/FDDI.md glossary/d-f.md#fddi +https://tarf.co.uk/Glossary/f/feature%20creep/ Glossary/f/feature creep.md glossary/d-f.md#feature-creep +https://tarf.co.uk/Glossary/f/Feature%20Test/ Glossary/f/Feature Test.md glossary/d-f.md#feature-test +https://tarf.co.uk/Glossary/f/Feature/ Glossary/f/Feature.md glossary/d-f.md#feature +https://tarf.co.uk/Glossary/f/FemtoCell/ Glossary/f/FemtoCell.md glossary/d-f.md#femtocell +https://tarf.co.uk/Glossary/f/FIPS%20140-2/ Glossary/f/FIPS 140-2.md glossary/d-f.md#fips-140-2 +https://tarf.co.uk/Glossary/f/FIPS/ Glossary/f/FIPS.md glossary/d-f.md#fips +https://tarf.co.uk/Glossary/f/Firewall/ Glossary/f/Firewall.md glossary/d-f.md#firewall +https://tarf.co.uk/Glossary/f/FNA/ Glossary/f/FNA.md glossary/d-f.md#fna +https://tarf.co.uk/Glossary/f/Formal%20Testing/ Glossary/f/Formal Testing.md glossary/d-f.md#formal-testing +https://tarf.co.uk/Glossary/f/Fortran/ Glossary/f/Fortran.md glossary/d-f.md#fortran +https://tarf.co.uk/Glossary/f/Forwarding%20plane/ Glossary/f/Forwarding plane.md glossary/d-f.md#forwarding-plane +https://tarf.co.uk/Glossary/f/FQDN/ Glossary/f/FQDN.md glossary/d-f.md#fqdn +https://tarf.co.uk/Glossary/f/Frame%20Relay/ Glossary/f/Frame Relay.md glossary/d-f.md#frame-relay +https://tarf.co.uk/Glossary/f/Frequent%20Releases/ Glossary/f/Frequent Releases.md glossary/d-f.md#frequent-releases +https://tarf.co.uk/Glossary/f/Frequently%20Asked%20Question/ Glossary/f/Frequently Asked Question.md glossary/d-f.md#frequently-asked-question +https://tarf.co.uk/Glossary/f/FSK/ Glossary/f/FSK.md glossary/d-f.md#fsk +https://tarf.co.uk/Glossary/f/FTP/ Glossary/f/FTP.md glossary/d-f.md#ftp +https://tarf.co.uk/Glossary/f/FTPS/ Glossary/f/FTPS.md glossary/d-f.md#ftps +https://tarf.co.uk/Glossary/f/Full%20duplex/ Glossary/f/Full duplex.md glossary/d-f.md#full-duplex +https://tarf.co.uk/Glossary/f/Function%20Point/ Glossary/f/Function Point.md glossary/d-f.md#function-point +https://tarf.co.uk/Glossary/f/Functional%20Requirement/ Glossary/f/Functional Requirement.md glossary/d-f.md#functional-requirement +https://tarf.co.uk/Glossary/f/Functional%20Testing/ Glossary/f/Functional Testing.md glossary/d-f.md#functional-testing +https://tarf.co.uk/Glossary/f/Fuzzy%20Front%20End/ Glossary/f/Fuzzy Front End.md glossary/d-f.md#fuzzy-front-end +https://tarf.co.uk/Glossary/f/Fuzzy%20Logic/ Glossary/f/Fuzzy Logic.md glossary/d-f.md#fuzzy-logic +https://tarf.co.uk/Glossary/f/FXO/ Glossary/f/FXO.md glossary/d-f.md#fxo +https://tarf.co.uk/Glossary/f/FXS/ Glossary/f/FXS.md glossary/d-f.md#fxs +https://tarf.co.uk/Glossary/g/G.711.1/ Glossary/g/G.711.1.md glossary/g-k.md#g7111 +https://tarf.co.uk/Glossary/g/G.711/ Glossary/g/G.711.md glossary/g-k.md#g711 +https://tarf.co.uk/Glossary/g/G.719/ Glossary/g/G.719.md glossary/g-k.md#g719 +https://tarf.co.uk/Glossary/g/G.722/ Glossary/g/G.722.md glossary/g-k.md#g722 +https://tarf.co.uk/Glossary/g/G.723.1/ Glossary/g/G.723.1.md glossary/g-k.md#g7231 +https://tarf.co.uk/Glossary/g/G.726/ Glossary/g/G.726.md glossary/g-k.md#g726 +https://tarf.co.uk/Glossary/g/G.729/ Glossary/g/G.729.md glossary/a-c.md#audio-codecs renamed to "Audio Codecs" +https://tarf.co.uk/Glossary/g/G.Fast/ Glossary/g/G.Fast.md glossary/g-k.md#gfast +https://tarf.co.uk/Glossary/g/g/ Glossary/g/g.md glossary/g-k.md letter index +https://tarf.co.uk/Glossary/g/Gantt%20chart/ Glossary/g/Gantt chart.md glossary/g-k.md#gantt-chart +https://tarf.co.uk/Glossary/g/gap%20analysis/ Glossary/g/gap analysis.md glossary/g-k.md#gap-analysis +https://tarf.co.uk/Glossary/g/Gate%20Checklist/ Glossary/g/Gate Checklist.md glossary/g-k.md#gate-checklist +https://tarf.co.uk/Glossary/g/Gate/ Glossary/g/Gate.md glossary/g-k.md#gate +https://tarf.co.uk/Glossary/g/GBE%20-%20GE/ Glossary/g/GBE - GE.md glossary/g-k.md#gbe-ge renamed to "GBE / GE" +https://tarf.co.uk/Glossary/g/GCHQ/ Glossary/g/GCHQ.md glossary/g-k.md#gchq +https://tarf.co.uk/Glossary/g/Geocast/ Glossary/g/Geocast.md glossary/g-k.md#geocast +https://tarf.co.uk/Glossary/g/GERAN/ Glossary/g/GERAN.md glossary/g-k.md#geran +https://tarf.co.uk/Glossary/g/GGSN/ Glossary/g/GGSN.md glossary/g-k.md#ggsn +https://tarf.co.uk/Glossary/g/Gherkin/ Glossary/g/Gherkin.md glossary/g-k.md#gherkin +https://tarf.co.uk/Glossary/g/Gigabit%20Ethernet/ Glossary/g/Gigabit Ethernet.md glossary/g-k.md#gigabit-ethernet +https://tarf.co.uk/Glossary/g/Git/ Glossary/g/Git.md glossary/g-k.md#git +https://tarf.co.uk/Glossary/g/Given%20When%20Then/ Glossary/g/Given When Then.md glossary/g-k.md#given-when-then +https://tarf.co.uk/Glossary/g/GMSC/ Glossary/g/GMSC.md glossary/g-k.md#gmsc +https://tarf.co.uk/Glossary/g/GNU/ Glossary/g/GNU.md glossary/g-k.md#gnu +https://tarf.co.uk/Glossary/g/Go/ Glossary/g/Go.md glossary/g-k.md#go +https://tarf.co.uk/Glossary/g/Goals/ Glossary/g/Goals.md glossary/g-k.md#goals +https://tarf.co.uk/Glossary/g/GoF/ Glossary/g/GoF.md glossary/g-k.md#gof +https://tarf.co.uk/Glossary/g/Google%20Cloud%20Platform/ Glossary/g/Google Cloud Platform.md glossary/g-k.md#google-cloud-platform +https://tarf.co.uk/Glossary/g/GPL/ Glossary/g/GPL.md glossary/g-k.md#gpl +https://tarf.co.uk/Glossary/g/GPRS/ Glossary/g/GPRS.md glossary/g-k.md#gprs +https://tarf.co.uk/Glossary/g/GSM%20AMR/ Glossary/g/GSM AMR.md glossary/g-k.md#gsm-amr +https://tarf.co.uk/Glossary/g/GSM-FR/ Glossary/g/GSM-FR.md glossary/g-k.md#gsm-fr +https://tarf.co.uk/Glossary/g/GSM-R/ Glossary/g/GSM-R.md glossary/g-k.md#gsm-r +https://tarf.co.uk/Glossary/g/GSM/ Glossary/g/GSM.md glossary/g-k.md#gsm +https://tarf.co.uk/Glossary/g/GSN/ Glossary/g/GSN.md glossary/g-k.md#gsn +https://tarf.co.uk/Glossary/g/The%20first%20example%20has%20two%20steps/ Glossary/g/The first example has two steps.md glossary/g-k.md#gherkin renamed to "Gherkin" +https://tarf.co.uk/Glossary/g/The%20second%20example%20has%20three%20steps/ Glossary/g/The second example has three steps.md glossary/g-k.md#gherkin renamed to "Gherkin" +https://tarf.co.uk/Glossary/h/H.248/ Glossary/h/H.248.md glossary/g-k.md#h248 +https://tarf.co.uk/Glossary/h/H.323/ Glossary/h/H.323.md glossary/g-k.md#h323 +https://tarf.co.uk/Glossary/h/h/ Glossary/h/h.md glossary/g-k.md letter index +https://tarf.co.uk/Glossary/h/Half%20Duplex/ Glossary/h/Half Duplex.md glossary/g-k.md#half-duplex +https://tarf.co.uk/Glossary/h/Happy%20Path/ Glossary/h/Happy Path.md glossary/g-k.md#happy-path +https://tarf.co.uk/Glossary/h/Hash%20Function/ Glossary/h/Hash Function.md glossary/g-k.md#hash-function +https://tarf.co.uk/Glossary/h/HDF/ Glossary/h/HDF.md glossary/g-k.md#hdf +https://tarf.co.uk/Glossary/h/HDLC/ Glossary/h/HDLC.md glossary/g-k.md#hdlc +https://tarf.co.uk/Glossary/h/HDSL/ Glossary/h/HDSL.md glossary/g-k.md#hdsl +https://tarf.co.uk/Glossary/h/Heartbeat%20Retrospective/ Glossary/h/Heartbeat Retrospective.md glossary/g-k.md#heartbeat-retrospective +https://tarf.co.uk/Glossary/h/HiFi%20Prototype/ Glossary/h/HiFi Prototype.md glossary/g-k.md#hifi-prototype +https://tarf.co.uk/Glossary/h/High%20Fidelity%20Prototype/ Glossary/h/High Fidelity Prototype.md glossary/g-k.md#high-fidelity-prototype +https://tarf.co.uk/Glossary/h/High%20Level%20Design/ Glossary/h/High Level Design.md glossary/g-k.md#high-level-design +https://tarf.co.uk/Glossary/h/HLR/ Glossary/h/HLR.md glossary/g-k.md#hlr +https://tarf.co.uk/Glossary/h/Hotfix/ Glossary/h/Hotfix.md glossary/g-k.md#hotfix +https://tarf.co.uk/Glossary/h/How%20Requirement/ Glossary/h/How Requirement.md glossary/g-k.md#how-requirement +https://tarf.co.uk/Glossary/h/How%20Well%20Requirement/ Glossary/h/How Well Requirement.md glossary/g-k.md#how-well-requirement +https://tarf.co.uk/Glossary/h/HSRP/ Glossary/h/HSRP.md glossary/g-k.md#hsrp +https://tarf.co.uk/Glossary/h/HSS/ Glossary/h/HSS.md glossary/g-k.md#hss +https://tarf.co.uk/Glossary/h/HTTP/ Glossary/h/HTTP.md glossary/g-k.md#http +https://tarf.co.uk/Glossary/h/HTTPS/ Glossary/h/HTTPS.md glossary/g-k.md#https +https://tarf.co.uk/Glossary/h/Hub/ Glossary/h/Hub.md glossary/g-k.md#hub +https://tarf.co.uk/Glossary/h/human%20factors/ Glossary/h/human factors.md glossary/g-k.md#human-factors +https://tarf.co.uk/Glossary/h/Hungarian%20notation/ Glossary/h/Hungarian notation.md glossary/g-k.md#hungarian-notation +https://tarf.co.uk/Glossary/i/BRI/ Glossary/i/BRI.md glossary/a-c.md#bri +https://tarf.co.uk/Glossary/i/i/ Glossary/i/i.md glossary/g-k.md letter index +https://tarf.co.uk/Glossary/i/IA/ Glossary/i/IA.md glossary/g-k.md#ia +https://tarf.co.uk/Glossary/i/IaaS/ Glossary/i/IaaS.md glossary/g-k.md#iaas +https://tarf.co.uk/Glossary/i/ICE/ Glossary/i/ICE.md glossary/g-k.md#ice +https://tarf.co.uk/Glossary/i/ICMP/ Glossary/i/ICMP.md glossary/g-k.md#icmp +https://tarf.co.uk/Glossary/i/ICMPv6/ Glossary/i/ICMPv6.md glossary/g-k.md#icmpv6 +https://tarf.co.uk/Glossary/i/IDE/ Glossary/i/IDE.md glossary/g-k.md#ide +https://tarf.co.uk/Glossary/i/IDQ/ Glossary/i/IDQ.md glossary/g-k.md#idq +https://tarf.co.uk/Glossary/i/IEC/ Glossary/i/IEC.md glossary/g-k.md#iec +https://tarf.co.uk/Glossary/i/IEEE%20802.1ah/ Glossary/i/IEEE 802.1ah.md glossary/g-k.md#ieee-8021ah +https://tarf.co.uk/Glossary/i/IEEE/ Glossary/i/IEEE.md glossary/g-k.md#ieee +https://tarf.co.uk/Glossary/i/IETF/ Glossary/i/IETF.md glossary/g-k.md#ietf +https://tarf.co.uk/Glossary/i/IGMP/ Glossary/i/IGMP.md glossary/g-k.md#igmp +https://tarf.co.uk/Glossary/i/IGP/ Glossary/i/IGP.md glossary/g-k.md#igp +https://tarf.co.uk/Glossary/i/IGRP/ Glossary/i/IGRP.md glossary/g-k.md#igrp +https://tarf.co.uk/Glossary/i/IIS/ Glossary/i/IIS.md glossary/g-k.md#iis +https://tarf.co.uk/Glossary/i/IKE/ Glossary/i/IKE.md glossary/g-k.md#ike +https://tarf.co.uk/Glossary/i/iLBC/ Glossary/i/iLBC.md glossary/g-k.md#ilbc +https://tarf.co.uk/Glossary/i/iManager/ Glossary/i/iManager.md glossary/g-k.md#imanager +https://tarf.co.uk/Glossary/i/IMAP/ Glossary/i/IMAP.md glossary/g-k.md#imap +https://tarf.co.uk/Glossary/i/Implementation%20Lead/ Glossary/i/Implementation Lead.md glossary/g-k.md#implementation-lead +https://tarf.co.uk/Glossary/i/Implementation/ Glossary/i/Implementation.md glossary/g-k.md#implementation +https://tarf.co.uk/Glossary/i/Implicit%20Change%20Control/ Glossary/i/Implicit Change Control.md glossary/g-k.md#implicit-change-control +https://tarf.co.uk/Glossary/i/Implicit%20Risk%20Management/ Glossary/i/Implicit Risk Management.md glossary/g-k.md#implicit-risk-management +https://tarf.co.uk/Glossary/i/IMS/ Glossary/i/IMS.md glossary/g-k.md#ims +https://tarf.co.uk/Glossary/i/IMSI/ Glossary/i/IMSI.md glossary/g-k.md#imsi +https://tarf.co.uk/Glossary/i/IN/ Glossary/i/IN.md glossary/g-k.md#in +https://tarf.co.uk/Glossary/i/INAP/ Glossary/i/INAP.md glossary/g-k.md#inap +https://tarf.co.uk/Glossary/i/Inch-Pebble/ Glossary/i/Inch-Pebble.md glossary/g-k.md#inch-pebble +https://tarf.co.uk/Glossary/i/Incremental%20Development/ Glossary/i/Incremental Development.md glossary/g-k.md#incremental-development +https://tarf.co.uk/Glossary/i/Informal%20Review/ Glossary/i/Informal Review.md glossary/g-k.md#informal-review +https://tarf.co.uk/Glossary/i/Informal%20Testing/ Glossary/i/Informal Testing.md glossary/g-k.md#informal-testing +https://tarf.co.uk/Glossary/i/information%20architecture/ Glossary/i/information architecture.md glossary/g-k.md#information-architecture +https://tarf.co.uk/Glossary/i/information%20design/ Glossary/i/information design.md glossary/g-k.md#information-design +https://tarf.co.uk/Glossary/i/Information%20Radiators/ Glossary/i/Information Radiators.md glossary/g-k.md#information-radiators +https://tarf.co.uk/Glossary/i/Ingress/ Glossary/i/Ingress.md glossary/g-k.md#ingress +https://tarf.co.uk/Glossary/i/Inspection/ Glossary/i/Inspection.md glossary/g-k.md#inspection +https://tarf.co.uk/Glossary/i/Inspector/ Glossary/i/Inspector.md glossary/g-k.md#inspector +https://tarf.co.uk/Glossary/i/Institute%20of%20Electrical%20and%20Electronics%20Engineers/ Glossary/i/Institute of Electrical and Electronics Engineers.md glossary/g-k.md#institute-of-electrical-and-electronics-engineers +https://tarf.co.uk/Glossary/i/Integrated%20Development%20Environment/ Glossary/i/Integrated Development Environment.md glossary/g-k.md#integrated-development-environment +https://tarf.co.uk/Glossary/i/Integration%20Test/ Glossary/i/Integration Test.md glossary/g-k.md#integration-test +https://tarf.co.uk/Glossary/i/Integration/ Glossary/i/Integration.md glossary/g-k.md#integration +https://tarf.co.uk/Glossary/i/International%20Organization%20for%20Standardization/ Glossary/i/International Organization for Standardization.md glossary/g-k.md#iso renamed to "ISO" +https://tarf.co.uk/Glossary/i/Internet%20Protocol%20Suite/ Glossary/i/Internet Protocol Suite.md glossary/g-k.md#internet-protocol-suite +https://tarf.co.uk/Glossary/i/Interpreted%20Language/ Glossary/i/Interpreted Language.md glossary/g-k.md#interpreted-language +https://tarf.co.uk/Glossary/i/Intrinsic%20Risk%20Management/ Glossary/i/Intrinsic Risk Management.md glossary/g-k.md#intrinsic-risk-management +https://tarf.co.uk/Glossary/i/INVEST/ Glossary/i/INVEST.md glossary/g-k.md#invest +https://tarf.co.uk/Glossary/i/IOS%20cisco%20OS/ Glossary/i/IOS cisco OS.md glossary/g-k.md#ios renamed to "IOS" +https://tarf.co.uk/Glossary/i/IPS/ Glossary/i/IPS.md glossary/g-k.md#ips +https://tarf.co.uk/Glossary/i/IPSC/ Glossary/i/IPSC.md glossary/g-k.md#ipsc +https://tarf.co.uk/Glossary/i/IPSec/ Glossary/i/IPSec.md glossary/g-k.md#ipsec +https://tarf.co.uk/Glossary/i/IPTV/ Glossary/i/IPTV.md glossary/g-k.md#iptv +https://tarf.co.uk/Glossary/i/IPv4/ Glossary/i/IPv4.md glossary/g-k.md#ipv4 +https://tarf.co.uk/Glossary/i/IPv6/ Glossary/i/IPv6.md glossary/g-k.md#ipv6 +https://tarf.co.uk/Glossary/i/ISDN/ Glossary/i/ISDN.md glossary/g-k.md#isdn +https://tarf.co.uk/Glossary/i/ISDN2/ Glossary/i/ISDN2.md glossary/g-k.md#isdn2 +https://tarf.co.uk/Glossary/i/ISDN30/ Glossary/i/ISDN30.md glossary/g-k.md#isdn30 +https://tarf.co.uk/Glossary/i/ISO/ Glossary/i/ISO.md glossary/g-k.md#iso +https://tarf.co.uk/Glossary/i/ISP/ Glossary/i/ISP.md glossary/g-k.md#isp +https://tarf.co.uk/Glossary/i/Issue%20Management/ Glossary/i/Issue Management.md glossary/g-k.md#issue-management +https://tarf.co.uk/Glossary/i/Issue%20tracker/ Glossary/i/Issue tracker.md glossary/g-k.md#issue-tracker +https://tarf.co.uk/Glossary/i/Issue/ Glossary/i/Issue.md glossary/g-k.md#issue +https://tarf.co.uk/Glossary/i/ISUP/ Glossary/i/ISUP.md glossary/g-k.md#isup +https://tarf.co.uk/Glossary/i/Item/ Glossary/i/Item.md glossary/g-k.md#item +https://tarf.co.uk/Glossary/i/Iteration/ Glossary/i/Iteration.md glossary/g-k.md#iteration +https://tarf.co.uk/Glossary/i/Iterative%20Development/ Glossary/i/Iterative Development.md glossary/g-k.md#iterative-development +https://tarf.co.uk/Glossary/i/ITIL/ Glossary/i/ITIL.md glossary/g-k.md#itil +https://tarf.co.uk/Glossary/i/ITU-T/ Glossary/i/ITU-T.md glossary/g-k.md#itu-t +https://tarf.co.uk/Glossary/i/ITU/ Glossary/i/ITU.md glossary/g-k.md#itu +https://tarf.co.uk/Glossary/i/IUP/ Glossary/i/IUP.md glossary/g-k.md#iup +https://tarf.co.uk/Glossary/i/IVR/ Glossary/i/IVR.md glossary/g-k.md#ivr +https://tarf.co.uk/Glossary/i/PRI/ Glossary/i/PRI.md glossary/o-r.md#pri +https://tarf.co.uk/Glossary/j/j/ Glossary/j/j.md glossary/g-k.md letter index +https://tarf.co.uk/Glossary/j/Java/ Glossary/j/Java.md glossary/g-k.md#java +https://tarf.co.uk/Glossary/j/Javascript/ Glossary/j/Javascript.md glossary/g-k.md#javascript +https://tarf.co.uk/Glossary/j/Jitter%20buffer/ Glossary/j/Jitter buffer.md glossary/g-k.md#jitter-buffer +https://tarf.co.uk/Glossary/j/Jitter/ Glossary/j/Jitter.md glossary/g-k.md#jitter +https://tarf.co.uk/Glossary/j/Joint%20Application%20Development/ Glossary/j/Joint Application Development.md glossary/g-k.md#joint-application-development +https://tarf.co.uk/Glossary/j/JSON-RPC/ Glossary/j/JSON-RPC.md glossary/g-k.md#json-rpc +https://tarf.co.uk/Glossary/j/JSON/ Glossary/j/JSON.md glossary/g-k.md#json +https://tarf.co.uk/Glossary/k/K%20%26%20R%20C/ Glossary/k/K & R C.md glossary/g-k.md#k-r-c +https://tarf.co.uk/Glossary/k/K%20%26%20R%20indent%20style/ Glossary/k/K & R indent style.md glossary/g-k.md#k-r-indent-style +https://tarf.co.uk/Glossary/k/K%20%26%20R/ Glossary/k/K & R.md glossary/g-k.md#k-r +https://tarf.co.uk/Glossary/k/k/ Glossary/k/k.md glossary/g-k.md letter index +https://tarf.co.uk/Glossary/k/Kanban%20Board/ Glossary/k/Kanban Board.md glossary/g-k.md#kanban-board +https://tarf.co.uk/Glossary/k/Kanban/ Glossary/k/Kanban.md glossary/g-k.md#kanban +https://tarf.co.uk/Glossary/k/KDL/ Glossary/k/KDL.md glossary/g-k.md#kdl +https://tarf.co.uk/Glossary/k/Kerberos/ Glossary/k/Kerberos.md glossary/g-k.md#kerberos +https://tarf.co.uk/Glossary/k/Kernel/ Glossary/k/Kernel.md glossary/g-k.md#kernel +https://tarf.co.uk/Glossary/k/KISS%20Principle/ Glossary/k/KISS Principle.md glossary/g-k.md#kiss-principle +https://tarf.co.uk/Glossary/k/Knowledge%20Management/ Glossary/k/Knowledge Management.md glossary/g-k.md#knowledge-management +https://tarf.co.uk/Glossary/k/KPI/ Glossary/k/KPI.md glossary/g-k.md#kpi +https://tarf.co.uk/Glossary/k/ksh/ Glossary/k/ksh.md glossary/g-k.md#ksh +https://tarf.co.uk/Glossary/l/l/ Glossary/l/l.md glossary/l-n.md letter index +https://tarf.co.uk/Glossary/l/L1/ Glossary/l/L1.md glossary/l-n.md#l1 +https://tarf.co.uk/Glossary/l/L2/ Glossary/l/L2.md glossary/l-n.md#l2 +https://tarf.co.uk/Glossary/l/L2F/ Glossary/l/L2F.md glossary/l-n.md#l2f +https://tarf.co.uk/Glossary/l/L2S/ Glossary/l/L2S.md glossary/l-n.md dropped +https://tarf.co.uk/Glossary/l/L2TP/ Glossary/l/L2TP.md glossary/l-n.md#l2tp +https://tarf.co.uk/Glossary/l/L2VPN/ Glossary/l/L2VPN.md glossary/l-n.md#l2vpn +https://tarf.co.uk/Glossary/l/L3VPN/ Glossary/l/L3VPN.md glossary/l-n.md#l3vpn +https://tarf.co.uk/Glossary/l/LAC/ Glossary/l/LAC.md glossary/l-n.md#lac +https://tarf.co.uk/Glossary/l/LACP/ Glossary/l/LACP.md glossary/l-n.md#lacp +https://tarf.co.uk/Glossary/l/LAG/ Glossary/l/LAG.md glossary/l-n.md#lag +https://tarf.co.uk/Glossary/l/LAN/ Glossary/l/LAN.md glossary/l-n.md#lan +https://tarf.co.uk/Glossary/l/LANE/ Glossary/l/LANE.md glossary/l-n.md#lane +https://tarf.co.uk/Glossary/l/LAS/ Glossary/l/LAS.md glossary/l-n.md dropped +https://tarf.co.uk/Glossary/l/Latency/ Glossary/l/Latency.md glossary/l-n.md#latency +https://tarf.co.uk/Glossary/l/Lawful%20intercept/ Glossary/l/Lawful intercept.md glossary/l-n.md#lawful-intercept +https://tarf.co.uk/Glossary/l/LCR/ Glossary/l/LCR.md glossary/l-n.md#lcr +https://tarf.co.uk/Glossary/l/LDAP/ Glossary/l/LDAP.md glossary/l-n.md#ldap +https://tarf.co.uk/Glossary/l/Lead%20Time/ Glossary/l/Lead Time.md glossary/l-n.md#lead-time +https://tarf.co.uk/Glossary/l/lean%20programming/ Glossary/l/lean programming.md glossary/l-n.md#lean-programming +https://tarf.co.uk/Glossary/l/Lean/ Glossary/l/Lean.md glossary/l-n.md#lean +https://tarf.co.uk/Glossary/l/Leased%20Line/ Glossary/l/Leased Line.md glossary/l-n.md#leased-line +https://tarf.co.uk/Glossary/l/LeSS/ Glossary/l/LeSS.md glossary/l-n.md#less +https://tarf.co.uk/Glossary/l/Lifecycle/ Glossary/l/Lifecycle.md glossary/l-n.md#lifecycle +https://tarf.co.uk/Glossary/l/Lines%20of%20Code/ Glossary/l/Lines of Code.md glossary/l-n.md#lines-of-code +https://tarf.co.uk/Glossary/l/Link/ Glossary/l/Link.md glossary/l-n.md dropped +https://tarf.co.uk/Glossary/l/Linux/ Glossary/l/Linux.md glossary/l-n.md#linux +https://tarf.co.uk/Glossary/l/lisp/ Glossary/l/lisp.md glossary/l-n.md#lisp +https://tarf.co.uk/Glossary/l/Lite/ Glossary/l/Lite.md glossary/l-n.md dropped +https://tarf.co.uk/Glossary/l/LL/ Glossary/l/LL.md glossary/l-n.md#ll +https://tarf.co.uk/Glossary/l/LNS/ Glossary/l/LNS.md glossary/l-n.md#lns +https://tarf.co.uk/Glossary/l/Local%20Build/ Glossary/l/Local Build.md glossary/l-n.md#local-build +https://tarf.co.uk/Glossary/l/Local%20Development%20Environment/ Glossary/l/Local Development Environment.md glossary/l-n.md#local-development-environment +https://tarf.co.uk/Glossary/l/Local%20Loop/ Glossary/l/Local Loop.md glossary/l-n.md#local-loop +https://tarf.co.uk/Glossary/l/Local%20Test%20Environment/ Glossary/l/Local Test Environment.md glossary/l-n.md#local-test-environment +https://tarf.co.uk/Glossary/l/LoFi%20Prototype/ Glossary/l/LoFi Prototype.md glossary/l-n.md#lofi-prototype +https://tarf.co.uk/Glossary/l/Low%20Fidelity%20Prototype/ Glossary/l/Low Fidelity Prototype.md glossary/l-n.md#low-fidelity-prototype +https://tarf.co.uk/Glossary/l/Low%20Level%20Design/ Glossary/l/Low Level Design.md glossary/l-n.md#low-level-design +https://tarf.co.uk/Glossary/l/LPS/ Glossary/l/LPS.md glossary/l-n.md dropped +https://tarf.co.uk/Glossary/l/LSP/ Glossary/l/LSP.md glossary/l-n.md#lsp +https://tarf.co.uk/Glossary/l/LSR/ Glossary/l/LSR.md glossary/l-n.md#lsr +https://tarf.co.uk/Glossary/l/LTE%20%284G%29/ Glossary/l/LTE (4G).md glossary/l-n.md#lte-4g +https://tarf.co.uk/Glossary/l/LTE%20and%20Mobile%20Internet/ Glossary/l/LTE and Mobile Internet.md glossary/l-n.md#lte-4g renamed to "LTE (4G)" +https://tarf.co.uk/Glossary/l/LTS/ Glossary/l/LTS.md glossary/l-n.md#lts +https://tarf.co.uk/Glossary/l/Lua/ Glossary/l/Lua.md glossary/l-n.md#lua +https://tarf.co.uk/Glossary/m/m/ Glossary/m/m.md glossary/l-n.md letter index +https://tarf.co.uk/Glossary/m/M2M/ Glossary/m/M2M.md glossary/l-n.md#m2m +https://tarf.co.uk/Glossary/m/MAC%20Address/ Glossary/m/MAC Address.md glossary/l-n.md#mac-address +https://tarf.co.uk/Glossary/m/MAC%20Flooding/ Glossary/m/MAC Flooding.md glossary/l-n.md#mac-flooding +https://tarf.co.uk/Glossary/m/MAC%20Spoofing/ Glossary/m/MAC Spoofing.md glossary/l-n.md#mac-spoofing +https://tarf.co.uk/Glossary/m/MAC/ Glossary/m/MAC.md glossary/l-n.md#mac +https://tarf.co.uk/Glossary/m/Machine%20code/ Glossary/m/Machine code.md glossary/l-n.md#machine-code +https://tarf.co.uk/Glossary/m/Macro%20Estimation/ Glossary/m/Macro Estimation.md glossary/l-n.md#macro-estimation +https://tarf.co.uk/Glossary/m/MAG/ Glossary/m/MAG.md glossary/l-n.md dropped +https://tarf.co.uk/Glossary/m/Maintenance%20Plan/ Glossary/m/Maintenance Plan.md glossary/l-n.md#maintenance-plan +https://tarf.co.uk/Glossary/m/Maintenance/ Glossary/m/Maintenance.md glossary/l-n.md#maintenance +https://tarf.co.uk/Glossary/m/MAN/ Glossary/m/MAN.md glossary/l-n.md#man +https://tarf.co.uk/Glossary/m/Management%20by%20Walking%20Around/ Glossary/m/Management by Walking Around.md glossary/l-n.md#management-by-walking-around +https://tarf.co.uk/Glossary/m/Management%20Plane/ Glossary/m/Management Plane.md glossary/l-n.md#management-plane +https://tarf.co.uk/Glossary/m/MANET/ Glossary/m/MANET.md glossary/l-n.md#manet +https://tarf.co.uk/Glossary/m/Manual%20Testing/ Glossary/m/Manual Testing.md glossary/l-n.md#manual-testing +https://tarf.co.uk/Glossary/m/MAP/ Glossary/m/MAP.md glossary/l-n.md#map +https://tarf.co.uk/Glossary/m/MAS/ Glossary/m/MAS.md glossary/l-n.md dropped +https://tarf.co.uk/Glossary/m/Material/ Glossary/m/Material.md glossary/l-n.md dropped +https://tarf.co.uk/Glossary/m/MBMS/ Glossary/m/MBMS.md glossary/l-n.md#mbms +https://tarf.co.uk/Glossary/m/MBORC/ Glossary/m/MBORC.md glossary/l-n.md#mborc +https://tarf.co.uk/Glossary/m/MD5/ Glossary/m/MD5.md glossary/l-n.md#md5 +https://tarf.co.uk/Glossary/m/MDF/ Glossary/m/MDF.md glossary/l-n.md#mdf +https://tarf.co.uk/Glossary/m/Mediation/ Glossary/m/Mediation.md glossary/l-n.md#mediation +https://tarf.co.uk/Glossary/m/MELP/ Glossary/m/MELP.md glossary/l-n.md#melp +https://tarf.co.uk/Glossary/m/Metric/ Glossary/m/Metric.md glossary/l-n.md#metric +https://tarf.co.uk/Glossary/m/MGCF/ Glossary/m/MGCF.md glossary/l-n.md#mgcf +https://tarf.co.uk/Glossary/m/MGCP/ Glossary/m/MGCP.md glossary/l-n.md#mgcp +https://tarf.co.uk/Glossary/m/MGW/ Glossary/m/MGW.md glossary/l-n.md#mgw +https://tarf.co.uk/Glossary/m/MIB/ Glossary/m/MIB.md glossary/l-n.md#mib +https://tarf.co.uk/Glossary/m/Micro%20Estimation/ Glossary/m/Micro Estimation.md glossary/l-n.md#micro-estimation +https://tarf.co.uk/Glossary/m/Microservice/ Glossary/m/Microservice.md glossary/l-n.md#microservice +https://tarf.co.uk/Glossary/m/Microstone/ Glossary/m/Microstone.md glossary/l-n.md#microstone +https://tarf.co.uk/Glossary/m/Mil-COTS/ Glossary/m/Mil-COTS.md glossary/l-n.md#mil-cots +https://tarf.co.uk/Glossary/m/Milestone%20Release/ Glossary/m/Milestone Release.md glossary/l-n.md#milestone-release +https://tarf.co.uk/Glossary/m/Milestone%20Retrospective/ Glossary/m/Milestone Retrospective.md glossary/l-n.md#milestone-retrospective +https://tarf.co.uk/Glossary/m/Milestone%20Schedule/ Glossary/m/Milestone Schedule.md glossary/l-n.md#milestone-schedule +https://tarf.co.uk/Glossary/m/Milestone/ Glossary/m/Milestone.md glossary/l-n.md#milestone +https://tarf.co.uk/Glossary/m/MIMO/ Glossary/m/MIMO.md glossary/l-n.md#mimo +https://tarf.co.uk/Glossary/m/Miniature%20Milestone/ Glossary/m/Miniature Milestone.md glossary/l-n.md#miniature-milestone +https://tarf.co.uk/Glossary/m/MME/ Glossary/m/MME.md glossary/l-n.md#mme +https://tarf.co.uk/Glossary/m/MMF/ Glossary/m/MMF.md glossary/l-n.md#mmf +https://tarf.co.uk/Glossary/m/MNC/ Glossary/m/MNC.md glossary/l-n.md#mnc +https://tarf.co.uk/Glossary/m/Mob%20Programming/ Glossary/m/Mob Programming.md glossary/l-n.md#mob-programming +https://tarf.co.uk/Glossary/m/Mobile%20Cell/ Glossary/m/Mobile Cell.md glossary/l-n.md#mobile-cell +https://tarf.co.uk/Glossary/m/Mobile%20Networks%202G-3G/ Glossary/m/Mobile Networks 2G-3G.md glossary/s-z.md#umts renamed to "UMTS" +https://tarf.co.uk/Glossary/m/Mock%20Objects/ Glossary/m/Mock Objects.md glossary/l-n.md#mock-objects +https://tarf.co.uk/Glossary/m/Model/ Glossary/m/Model.md glossary/l-n.md#model +https://tarf.co.uk/Glossary/m/Modeling/ Glossary/m/Modeling.md glossary/l-n.md#modelling renamed to "Modelling" +https://tarf.co.uk/Glossary/m/Moderator/ Glossary/m/Moderator.md glossary/l-n.md#moderator +https://tarf.co.uk/Glossary/m/MOS/ Glossary/m/MOS.md glossary/l-n.md#mos +https://tarf.co.uk/Glossary/m/MP3/ Glossary/m/MP3.md glossary/l-n.md#mp3 +https://tarf.co.uk/Glossary/m/MPEG/ Glossary/m/MPEG.md glossary/l-n.md#mpeg +https://tarf.co.uk/Glossary/m/MPEG4/ Glossary/m/MPEG4.md glossary/l-n.md#mpeg4 +https://tarf.co.uk/Glossary/m/MPF/ Glossary/m/MPF.md glossary/l-n.md#mpf +https://tarf.co.uk/Glossary/m/MPS/ Glossary/m/MPS.md glossary/l-n.md dropped +https://tarf.co.uk/Glossary/m/MQTT/ Glossary/m/MQTT.md glossary/l-n.md#mqtt +https://tarf.co.uk/Glossary/m/MRF/ Glossary/m/MRF.md glossary/l-n.md#mrf +https://tarf.co.uk/Glossary/m/MRS/ Glossary/m/MRS.md glossary/l-n.md#mrs +https://tarf.co.uk/Glossary/m/MRTIE/ Glossary/m/MRTIE.md glossary/l-n.md#mrtie +https://tarf.co.uk/Glossary/m/MSAN/ Glossary/m/MSAN.md glossary/l-n.md#msan +https://tarf.co.uk/Glossary/m/MSC/ Glossary/m/MSC.md glossary/l-n.md#msc +https://tarf.co.uk/Glossary/m/MTP/ Glossary/m/MTP.md glossary/l-n.md#mtp +https://tarf.co.uk/Glossary/m/MTR/ Glossary/m/MTR.md glossary/l-n.md#mtr +https://tarf.co.uk/Glossary/m/MTU/ Glossary/m/MTU.md glossary/l-n.md#mtu +https://tarf.co.uk/Glossary/m/Multicast/ Glossary/m/Multicast.md glossary/l-n.md#multicast +https://tarf.co.uk/Glossary/m/Multiplex/ Glossary/m/Multiplex.md glossary/l-n.md#multiplex +https://tarf.co.uk/Glossary/m/Mutex/ Glossary/m/Mutex.md glossary/l-n.md#mutex +https://tarf.co.uk/Glossary/m/Mutual%20Exclusion/ Glossary/m/Mutual Exclusion.md glossary/l-n.md#mutual-exclusion +https://tarf.co.uk/Glossary/m/MVNE/ Glossary/m/MVNE.md glossary/l-n.md#mvne +https://tarf.co.uk/Glossary/m/MVNO/ Glossary/m/MVNO.md glossary/l-n.md#mvno +https://tarf.co.uk/Glossary/m/MVP/ Glossary/m/MVP.md glossary/l-n.md#mvp +https://tarf.co.uk/Glossary/n/n/ Glossary/n/n.md glossary/l-n.md letter index +https://tarf.co.uk/Glossary/n/NaaS/ Glossary/n/NaaS.md glossary/l-n.md#naas +https://tarf.co.uk/Glossary/n/NAPT/ Glossary/n/NAPT.md glossary/l-n.md#napt +https://tarf.co.uk/Glossary/n/NAS/ Glossary/n/NAS.md glossary/l-n.md#nas +https://tarf.co.uk/Glossary/n/NAT/ Glossary/n/NAT.md glossary/l-n.md#nat +https://tarf.co.uk/Glossary/n/Native%20Risk%20Management/ Glossary/n/Native Risk Management.md glossary/l-n.md#native-risk-management +https://tarf.co.uk/Glossary/n/NBAP/ Glossary/n/NBAP.md glossary/l-n.md#nbap +https://tarf.co.uk/Glossary/n/NCSC/ Glossary/n/NCSC.md glossary/l-n.md#ncsc +https://tarf.co.uk/Glossary/n/Network%20Topologies/ Glossary/n/Network Topologies.md glossary/l-n.md#network-topologies +https://tarf.co.uk/Glossary/n/NFS/ Glossary/n/NFS.md glossary/l-n.md#nfs +https://tarf.co.uk/Glossary/n/NGN/ Glossary/n/NGN.md glossary/l-n.md#ngn +https://tarf.co.uk/Glossary/n/NGWFQ/ Glossary/n/NGWFQ.md glossary/l-n.md#ngwfq +https://tarf.co.uk/Glossary/n/Niko-niko%20Calendar/ Glossary/n/Niko-niko Calendar.md glossary/l-n.md#niko-niko-calendar +https://tarf.co.uk/Glossary/n/NIST/ Glossary/n/NIST.md glossary/l-n.md#nist +https://tarf.co.uk/Glossary/n/NNI/ Glossary/n/NNI.md glossary/l-n.md#nni +https://tarf.co.uk/Glossary/n/NNTP/ Glossary/n/NNTP.md glossary/l-n.md#nntp +https://tarf.co.uk/Glossary/n/NOC/ Glossary/n/NOC.md glossary/l-n.md#noc +https://tarf.co.uk/Glossary/n/Node%20B/ Glossary/n/Node B.md glossary/l-n.md#node-b +https://tarf.co.uk/Glossary/n/Nominal%20Path/ Glossary/n/Nominal Path.md glossary/l-n.md#nominal-path 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glossary/o-r.md#odf +https://tarf.co.uk/Glossary/o/OFC/ Glossary/o/OFC.md glossary/o-r.md#ofc +https://tarf.co.uk/Glossary/o/Ofcom/ Glossary/o/Ofcom.md glossary/o-r.md#ofcom +https://tarf.co.uk/Glossary/o/OFDMA/ Glossary/o/OFDMA.md glossary/o-r.md#ofdma +https://tarf.co.uk/Glossary/o/OO/ Glossary/o/OO.md glossary/o-r.md#oo +https://tarf.co.uk/Glossary/o/Operations%20Plan/ Glossary/o/Operations Plan.md glossary/o-r.md#operations-plan +https://tarf.co.uk/Glossary/o/OPUS/ Glossary/o/OPUS.md glossary/o-r.md#opus +https://tarf.co.uk/Glossary/o/OS%20X/ Glossary/o/OS X.md glossary/o-r.md#os-x +https://tarf.co.uk/Glossary/o/OSA-FC/ Glossary/o/OSA-FC.md glossary/o-r.md#osa-fc +https://tarf.co.uk/Glossary/o/OSPF/ Glossary/o/OSPF.md glossary/o-r.md#ospf +https://tarf.co.uk/Glossary/o/OSS/ Glossary/o/OSS.md glossary/o-r.md#oss +https://tarf.co.uk/Glossary/o/OTN/ Glossary/o/OTN.md glossary/o-r.md#otn +https://tarf.co.uk/Glossary/o/Out-of-order%20delivery/ Glossary/o/Out-of-order delivery.md glossary/o-r.md#out-of-order-delivery +https://tarf.co.uk/Glossary/o/Overlap%20Dialling/ Glossary/o/Overlap Dialling.md glossary/o-r.md#overlap-dialling +https://tarf.co.uk/Glossary/p/p/ Glossary/p/p.md glossary/o-r.md letter index +https://tarf.co.uk/Glossary/p/PaaS/ Glossary/p/PaaS.md glossary/o-r.md#paas +https://tarf.co.uk/Glossary/p/packet%20sniffing/ Glossary/p/packet sniffing.md glossary/o-r.md#packet-sniffing +https://tarf.co.uk/Glossary/p/Packet%20Switched/ Glossary/p/Packet Switched.md glossary/o-r.md#packet-switched +https://tarf.co.uk/Glossary/p/PAF/ Glossary/p/PAF.md glossary/o-r.md#paf +https://tarf.co.uk/Glossary/p/Pair%20Programming/ Glossary/p/Pair Programming.md glossary/o-r.md#pair-programming +https://tarf.co.uk/Glossary/p/PAP/ Glossary/p/PAP.md glossary/o-r.md#pap +https://tarf.co.uk/Glossary/p/Parametric%20Estimation/ Glossary/p/Parametric Estimation.md glossary/o-r.md#parametric-estimation +https://tarf.co.uk/Glossary/p/Pascal/ Glossary/p/Pascal.md glossary/o-r.md#pascal +https://tarf.co.uk/Glossary/p/Pattern/ Glossary/p/Pattern.md glossary/o-r.md#pattern +https://tarf.co.uk/Glossary/p/PCM/ Glossary/p/PCM.md glossary/o-r.md#pcm +https://tarf.co.uk/Glossary/p/PCP/ Glossary/p/PCP.md glossary/o-r.md#pcp +https://tarf.co.uk/Glossary/p/PCRF/ Glossary/p/PCRF.md glossary/o-r.md#pcrf +https://tarf.co.uk/Glossary/p/PCS/ Glossary/p/PCS.md glossary/o-r.md#pcs +https://tarf.co.uk/Glossary/p/PDCP/ Glossary/p/PDCP.md glossary/o-r.md#pdcp +https://tarf.co.uk/Glossary/p/PDH/ Glossary/p/PDH.md glossary/o-r.md#pdh +https://tarf.co.uk/Glossary/p/PDU/ Glossary/p/PDU.md glossary/o-r.md#pdu +https://tarf.co.uk/Glossary/p/PEAP/ Glossary/p/PEAP.md glossary/o-r.md#peap +https://tarf.co.uk/Glossary/p/peer%20review/ Glossary/p/peer review.md glossary/o-r.md#peer-review +https://tarf.co.uk/Glossary/p/Pen%20testing/ Glossary/p/Pen testing.md glossary/o-r.md#pen-testing +https://tarf.co.uk/Glossary/p/PER/ Glossary/p/PER.md glossary/o-r.md#per 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glossary/o-r.md#planning-and-tracking-lead +https://tarf.co.uk/Glossary/p/Planning%20Poker/ Glossary/p/Planning Poker.md glossary/o-r.md#planning-poker +https://tarf.co.uk/Glossary/p/PLL/ Glossary/p/PLL.md glossary/o-r.md#pll +https://tarf.co.uk/Glossary/p/PNT/ Glossary/p/PNT.md glossary/o-r.md#pnt +https://tarf.co.uk/Glossary/p/Points/ Glossary/p/Points.md glossary/o-r.md#points +https://tarf.co.uk/Glossary/p/polymorphism/ Glossary/p/polymorphism.md glossary/o-r.md#polymorphism +https://tarf.co.uk/Glossary/p/POP/ Glossary/p/POP.md glossary/o-r.md#pop +https://tarf.co.uk/Glossary/p/portability/ Glossary/p/portability.md glossary/o-r.md#portability +https://tarf.co.uk/Glossary/p/POSIX/ Glossary/p/POSIX.md glossary/o-r.md#posix +https://tarf.co.uk/Glossary/p/Postmortem/ Glossary/p/Postmortem.md glossary/o-r.md#postmortem +https://tarf.co.uk/Glossary/p/POTS/ Glossary/p/POTS.md glossary/o-r.md#pots +https://tarf.co.uk/Glossary/p/PPP/ Glossary/p/PPP.md glossary/o-r.md#ppp +https://tarf.co.uk/Glossary/p/PPPoE/ Glossary/p/PPPoE.md glossary/o-r.md#pppoe +https://tarf.co.uk/Glossary/p/PPTP/ Glossary/p/PPTP.md glossary/o-r.md#pptp +https://tarf.co.uk/Glossary/p/Preemption/ Glossary/p/Preemption.md glossary/o-r.md#preemption +https://tarf.co.uk/Glossary/p/Preview/ Glossary/p/Preview.md glossary/o-r.md#preview +https://tarf.co.uk/Glossary/p/PRINCE2/ Glossary/p/PRINCE2.md glossary/o-r.md#prince2 +https://tarf.co.uk/Glossary/p/Process%20Flow/ Glossary/p/Process Flow.md glossary/o-r.md#process-flow +https://tarf.co.uk/Glossary/p/Process/ Glossary/p/Process.md glossary/o-r.md#process +https://tarf.co.uk/Glossary/p/Product%20Owner/ Glossary/p/Product Owner.md glossary/o-r.md#product-owner +https://tarf.co.uk/Glossary/p/Product%20Release/ Glossary/p/Product Release.md glossary/o-r.md#product-release +https://tarf.co.uk/Glossary/p/programming%20language/ Glossary/p/programming language.md glossary/o-r.md#programming-language 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Glossary/q/q.md glossary/o-r.md letter index +https://tarf.co.uk/Glossary/q/QA%20Lead/ Glossary/q/QA Lead.md glossary/o-r.md#qa-lead +https://tarf.co.uk/Glossary/q/QAM/ Glossary/q/QAM.md glossary/o-r.md#qam +https://tarf.co.uk/Glossary/q/QoS/ Glossary/q/QoS.md glossary/o-r.md#qos +https://tarf.co.uk/Glossary/q/QSIG/ Glossary/q/QSIG.md glossary/o-r.md#qsig +https://tarf.co.uk/Glossary/q/Quality%20Assurance%20Plan/ Glossary/q/Quality Assurance Plan.md glossary/o-r.md#quality-assurance-plan +https://tarf.co.uk/Glossary/q/Quality%20Assurance/ Glossary/q/Quality Assurance.md glossary/o-r.md#quality-assurance +https://tarf.co.uk/Glossary/q/Quality%20Control/ Glossary/q/Quality Control.md glossary/o-r.md#quality-control +https://tarf.co.uk/Glossary/q/Quality%20Plan/ Glossary/q/Quality Plan.md glossary/o-r.md#quality-plan +https://tarf.co.uk/Glossary/q/Quality/ Glossary/q/Quality.md glossary/o-r.md#quality +https://tarf.co.uk/Glossary/q/Quick%20Design%20Session/ Glossary/q/Quick Design Session.md glossary/o-r.md#quick-design-session +https://tarf.co.uk/Glossary/r/R%20Language/ Glossary/r/R Language.md glossary/o-r.md#r-language +https://tarf.co.uk/Glossary/r/r/ Glossary/r/r.md glossary/o-r.md letter index +https://tarf.co.uk/Glossary/r/RACI/ Glossary/r/RACI.md glossary/o-r.md#raci +https://tarf.co.uk/Glossary/r/RAD%20Environment/ Glossary/r/RAD Environment.md glossary/o-r.md#rad-environment +https://tarf.co.uk/Glossary/r/RAD/ Glossary/r/RAD.md glossary/o-r.md#rad +https://tarf.co.uk/Glossary/r/Radius/ Glossary/r/Radius.md glossary/o-r.md#radius +https://tarf.co.uk/Glossary/r/Rainbow/ Glossary/r/Rainbow.md glossary/o-r.md dropped +https://tarf.co.uk/Glossary/r/RAN/ Glossary/r/RAN.md glossary/o-r.md#ran +https://tarf.co.uk/Glossary/r/RANAP/ Glossary/r/RANAP.md glossary/o-r.md#ranap +https://tarf.co.uk/Glossary/r/RANCID/ Glossary/r/RANCID.md glossary/o-r.md#rancid +https://tarf.co.uk/Glossary/r/Rapid%20Application%20Development/ Glossary/r/Rapid Application Development.md glossary/o-r.md#rapid-application-development +https://tarf.co.uk/Glossary/r/RARP/ Glossary/r/RARP.md glossary/o-r.md#rarp +https://tarf.co.uk/Glossary/r/RAS/ Glossary/r/RAS.md glossary/o-r.md#ras +https://tarf.co.uk/Glossary/r/RDBMS/ Glossary/r/RDBMS.md glossary/o-r.md#rdbms +https://tarf.co.uk/Glossary/r/RDP/ Glossary/r/RDP.md glossary/o-r.md#rdp +https://tarf.co.uk/Glossary/r/Reading%20Inspection/ Glossary/r/Reading Inspection.md glossary/o-r.md#reading-inspection +https://tarf.co.uk/Glossary/r/refactoring/ Glossary/r/refactoring.md glossary/o-r.md#refactoring +https://tarf.co.uk/Glossary/r/Reference/ Glossary/r/Reference.md glossary/o-r.md dropped +https://tarf.co.uk/Glossary/r/regression%20testing/ Glossary/r/regression testing.md glossary/o-r.md#regression-testing +https://tarf.co.uk/Glossary/r/Regular%20expression/ Glossary/r/Regular expression.md glossary/o-r.md#regular-expression +https://tarf.co.uk/Glossary/r/Relative%20Estimation/ Glossary/r/Relative Estimation.md glossary/o-r.md#relative-estimation +https://tarf.co.uk/Glossary/r/Release%20Management/ Glossary/r/Release Management.md glossary/o-r.md#release-management +https://tarf.co.uk/Glossary/r/Release%20Test/ Glossary/r/Release Test.md glossary/o-r.md#release-test +https://tarf.co.uk/Glossary/r/Release/ Glossary/r/Release.md glossary/o-r.md#release +https://tarf.co.uk/Glossary/r/Requirement/ Glossary/r/Requirement.md glossary/o-r.md#requirement +https://tarf.co.uk/Glossary/r/Requirements%20Lead/ Glossary/r/Requirements Lead.md glossary/o-r.md#requirements-lead +https://tarf.co.uk/Glossary/r/Requirements/ Glossary/r/Requirements.md glossary/o-r.md#requirements +https://tarf.co.uk/Glossary/r/REST/ Glossary/r/REST.md glossary/o-r.md#rest +https://tarf.co.uk/Glossary/r/Review/ Glossary/r/Review.md glossary/o-r.md#review +https://tarf.co.uk/Glossary/r/Reviewer/ Glossary/r/Reviewer.md glossary/o-r.md#reviewer +https://tarf.co.uk/Glossary/r/Revision%20Control/ Glossary/r/Revision Control.md glossary/o-r.md#revision-control +https://tarf.co.uk/Glossary/r/Revision/ Glossary/r/Revision.md glossary/o-r.md#revision +https://tarf.co.uk/Glossary/r/Rework/ Glossary/r/Rework.md glossary/o-r.md#rework +https://tarf.co.uk/Glossary/r/RFC/ Glossary/r/RFC.md glossary/o-r.md#rfc +https://tarf.co.uk/Glossary/r/RIP/ Glossary/r/RIP.md glossary/o-r.md#rip +https://tarf.co.uk/Glossary/r/Risk%20Analysis/ Glossary/r/Risk Analysis.md glossary/o-r.md#risk-analysis +https://tarf.co.uk/Glossary/r/Risk%20Identification/ Glossary/r/Risk Identification.md glossary/o-r.md#risk-identification +https://tarf.co.uk/Glossary/r/Risk%20List/ Glossary/r/Risk List.md glossary/o-r.md#risk-list +https://tarf.co.uk/Glossary/r/Risk%20Management/ Glossary/r/Risk Management.md glossary/o-r.md#risk-management +https://tarf.co.uk/Glossary/r/Risk%20Mitigation/ Glossary/r/Risk Mitigation.md glossary/o-r.md#risk-mitigation +https://tarf.co.uk/Glossary/r/Risk%20Reward%20Matric/ Glossary/r/Risk Reward Matric.md glossary/o-r.md#risk-reward-matrix renamed to "Risk Reward Matrix" +https://tarf.co.uk/Glossary/r/Risk/ Glossary/r/Risk.md glossary/o-r.md#risk +https://tarf.co.uk/Glossary/r/RNC/ Glossary/r/RNC.md glossary/o-r.md#rnc +https://tarf.co.uk/Glossary/r/RNSAP/ Glossary/r/RNSAP.md glossary/o-r.md#rnsap +https://tarf.co.uk/Glossary/r/Role-feature-reason/ Glossary/r/Role-feature-reason.md glossary/o-r.md#role-feature-reason +https://tarf.co.uk/Glossary/r/Rolling%20Wave%20Planning/ Glossary/r/Rolling Wave Planning.md glossary/o-r.md#rolling-wave-planning +https://tarf.co.uk/Glossary/r/Round%20Robin/ Glossary/r/Round Robin.md glossary/o-r.md#round-robin +https://tarf.co.uk/Glossary/r/Router/ Glossary/r/Router.md glossary/o-r.md#router +https://tarf.co.uk/Glossary/r/RPC/ Glossary/r/RPC.md glossary/o-r.md#rpc +https://tarf.co.uk/Glossary/r/RRC/ Glossary/r/RRC.md glossary/o-r.md#rrc +https://tarf.co.uk/Glossary/r/RSTP/ Glossary/r/RSTP.md glossary/o-r.md#rstp +https://tarf.co.uk/Glossary/r/RSVP/ Glossary/r/RSVP.md glossary/o-r.md#rsvp +https://tarf.co.uk/Glossary/r/RTCP/ Glossary/r/RTCP.md glossary/o-r.md#rtcp +https://tarf.co.uk/Glossary/r/RTOS/ Glossary/r/RTOS.md glossary/o-r.md#rtos +https://tarf.co.uk/Glossary/r/RTP/ Glossary/r/RTP.md glossary/o-r.md#rtp +https://tarf.co.uk/Glossary/r/RTSP/ Glossary/r/RTSP.md glossary/o-r.md#rtsp +https://tarf.co.uk/Glossary/r/Ruby%20on%20rails/ Glossary/r/Ruby on rails.md glossary/o-r.md#ruby-on-rails +https://tarf.co.uk/Glossary/r/Ruby/ Glossary/r/Ruby.md glossary/o-r.md#ruby +https://tarf.co.uk/Glossary/r/Rule%20of%20Simplicity/ Glossary/r/Rule of Simplicity.md glossary/o-r.md#rule-of-simplicity +https://tarf.co.uk/Glossary/r/RUP/ Glossary/r/RUP.md glossary/o-r.md#rup +https://tarf.co.uk/Glossary/s/S-%20Tag/ Glossary/s/S- Tag.md glossary/s-z.md#s-tag renamed to "S-Tag" +https://tarf.co.uk/Glossary/s/S-GW/ Glossary/s/S-GW.md glossary/s-z.md#s-gw +https://tarf.co.uk/Glossary/s/s/ Glossary/s/s.md glossary/s-z.md letter index +https://tarf.co.uk/Glossary/s/SAAL/ Glossary/s/SAAL.md glossary/s-z.md#saal +https://tarf.co.uk/Glossary/s/SaaS/ Glossary/s/SaaS.md glossary/s-z.md#saas +https://tarf.co.uk/Glossary/s/SAE/ Glossary/s/SAE.md glossary/s-z.md#sae +https://tarf.co.uk/Glossary/s/SAFe/ Glossary/s/SAFe.md glossary/s-z.md#safe +https://tarf.co.uk/Glossary/s/SBC/ Glossary/s/SBC.md glossary/s-z.md#sbc +https://tarf.co.uk/Glossary/s/SC-FDMA/ Glossary/s/SC-FDMA.md glossary/s-z.md#sc-fdma +https://tarf.co.uk/Glossary/s/Scala/ Glossary/s/Scala.md glossary/s-z.md#scala +https://tarf.co.uk/Glossary/s/Scaled%20Agile/ Glossary/s/Scaled Agile.md glossary/s-z.md#scaled-agile +https://tarf.co.uk/Glossary/s/SCCP/ Glossary/s/SCCP.md glossary/s-z.md#sccp +https://tarf.co.uk/Glossary/s/Scenario/ Glossary/s/Scenario.md glossary/s-z.md#scenario +https://tarf.co.uk/Glossary/s/Schedule/ Glossary/s/Schedule.md glossary/s-z.md#schedule +https://tarf.co.uk/Glossary/s/Scheduler/ Glossary/s/Scheduler.md glossary/s-z.md#scheduler +https://tarf.co.uk/Glossary/s/SCM/ Glossary/s/SCM.md glossary/s-z.md#scm +https://tarf.co.uk/Glossary/s/Scratch/ Glossary/s/Scratch.md glossary/s-z.md#scratch +https://tarf.co.uk/Glossary/s/Scribe/ Glossary/s/Scribe.md glossary/s-z.md#scribe +https://tarf.co.uk/Glossary/s/Scrum%20Master/ Glossary/s/Scrum Master.md glossary/s-z.md#scrum-master +https://tarf.co.uk/Glossary/s/Scrum%20of%20Scrums/ Glossary/s/Scrum of Scrums.md glossary/s-z.md#scrum-of-scrums +https://tarf.co.uk/Glossary/s/Scrum/ Glossary/s/Scrum.md glossary/s-z.md#scrum +https://tarf.co.uk/Glossary/s/SCTP/ Glossary/s/SCTP.md glossary/s-z.md#sctp +https://tarf.co.uk/Glossary/s/SDES/ Glossary/s/SDES.md glossary/s-z.md#sdes +https://tarf.co.uk/Glossary/s/SDH/ Glossary/s/SDH.md glossary/s-z.md#sdh +https://tarf.co.uk/Glossary/s/SDK/ Glossary/s/SDK.md glossary/s-z.md#sdk +https://tarf.co.uk/Glossary/s/SDLC/ Glossary/s/SDLC.md glossary/s-z.md#sdlc +https://tarf.co.uk/Glossary/s/SDMA/ Glossary/s/SDMA.md glossary/s-z.md#sdma +https://tarf.co.uk/Glossary/s/SDN/ Glossary/s/SDN.md glossary/s-z.md#sdn +https://tarf.co.uk/Glossary/s/SDP/ Glossary/s/SDP.md glossary/s-z.md#sdp +https://tarf.co.uk/Glossary/s/SDSL/ Glossary/s/SDSL.md glossary/s-z.md#sdsl +https://tarf.co.uk/Glossary/s/Sed/ Glossary/s/Sed.md glossary/s-z.md#sed +https://tarf.co.uk/Glossary/s/Semaphore/ Glossary/s/Semaphore.md glossary/s-z.md#semaphore +https://tarf.co.uk/Glossary/s/Sematic%20Versioning/ Glossary/s/Sematic Versioning.md glossary/s-z.md#semantic-versioning renamed to "Semantic Versioning" +https://tarf.co.uk/Glossary/s/Sequence%20Model/ Glossary/s/Sequence Model.md glossary/s-z.md#sequence-model +https://tarf.co.uk/Glossary/s/SF/ Glossary/s/SF.md glossary/s-z.md#sf +https://tarf.co.uk/Glossary/s/SFTP/ Glossary/s/SFTP.md glossary/s-z.md#sftp +https://tarf.co.uk/Glossary/s/SGML/ Glossary/s/SGML.md glossary/s-z.md#sgml +https://tarf.co.uk/Glossary/s/SGSN/ Glossary/s/SGSN.md glossary/s-z.md#sgsn +https://tarf.co.uk/Glossary/s/SGW/ Glossary/s/SGW.md glossary/s-z.md#sgw +https://tarf.co.uk/Glossary/s/Sh/ Glossary/s/Sh.md glossary/s-z.md#sh +https://tarf.co.uk/Glossary/s/SHA/ Glossary/s/SHA.md glossary/s-z.md#sha +https://tarf.co.uk/Glossary/s/Shell%20Scripting/ Glossary/s/Shell Scripting.md glossary/s-z.md#shell-scripting +https://tarf.co.uk/Glossary/s/Sidetone/ Glossary/s/Sidetone.md glossary/s-z.md#sidetone +https://tarf.co.uk/Glossary/s/Sign%20Up/ Glossary/s/Sign Up.md glossary/s-z.md#sign-up +https://tarf.co.uk/Glossary/s/SIM/ Glossary/s/SIM.md glossary/s-z.md#sim +https://tarf.co.uk/Glossary/s/Simple%20Design/ Glossary/s/Simple Design.md glossary/s-z.md#simple-design +https://tarf.co.uk/Glossary/s/SIMPLE/ Glossary/s/SIMPLE.md glossary/s-z.md#simple +https://tarf.co.uk/Glossary/s/Simplex/ Glossary/s/Simplex.md glossary/s-z.md#simplex +https://tarf.co.uk/Glossary/s/Single%20Step%20Test/ Glossary/s/Single Step Test.md glossary/s-z.md#single-step-test +https://tarf.co.uk/Glossary/s/SIP%20Trunk/ Glossary/s/SIP Trunk.md glossary/s-z.md#sip-trunk +https://tarf.co.uk/Glossary/s/SIP/ Glossary/s/SIP.md glossary/s-z.md#sip +https://tarf.co.uk/Glossary/s/SISO/ Glossary/s/SISO.md glossary/s-z.md#siso +https://tarf.co.uk/Glossary/s/Skew/ Glossary/s/Skew.md glossary/s-z.md#skew +https://tarf.co.uk/Glossary/s/SLA/ Glossary/s/SLA.md glossary/s-z.md#sla +https://tarf.co.uk/Glossary/s/SLIP/ Glossary/s/SLIP.md glossary/s-z.md#slip +https://tarf.co.uk/Glossary/s/SME/ Glossary/s/SME.md glossary/s-z.md#sme +https://tarf.co.uk/Glossary/s/Smoke%20Test/ Glossary/s/Smoke Test.md glossary/s-z.md#smoke-test +https://tarf.co.uk/Glossary/s/smoke%20testing/ Glossary/s/smoke testing.md glossary/s-z.md#smoke-testing +https://tarf.co.uk/Glossary/s/SMP/ Glossary/s/SMP.md glossary/s-z.md#smp +https://tarf.co.uk/Glossary/s/SMPF/ Glossary/s/SMPF.md glossary/s-z.md#smpf +https://tarf.co.uk/Glossary/s/SMSC/ Glossary/s/SMSC.md glossary/s-z.md#smsc +https://tarf.co.uk/Glossary/s/Snake%20Case/ Glossary/s/Snake Case.md glossary/s-z.md#snake-case +https://tarf.co.uk/Glossary/s/SNMP/ Glossary/s/SNMP.md glossary/s-z.md#snmp +https://tarf.co.uk/Glossary/s/SNTP/ Glossary/s/SNTP.md glossary/s-z.md#sntp +https://tarf.co.uk/Glossary/s/SOA/ Glossary/s/SOA.md glossary/s-z.md#soa +https://tarf.co.uk/Glossary/s/SOAP/ Glossary/s/SOAP.md glossary/s-z.md#soap +https://tarf.co.uk/Glossary/s/Softswitch/ Glossary/s/Softswitch.md glossary/s-z.md#softswitch +https://tarf.co.uk/Glossary/s/Software%20Change%20Request/ Glossary/s/Software Change Request.md glossary/s-z.md#software-change-request +https://tarf.co.uk/Glossary/s/Software%20Configuration%20Management/ Glossary/s/Software Configuration Management.md glossary/s-z.md#software-configuration-management +https://tarf.co.uk/Glossary/s/Software%20Development%20Plan/ Glossary/s/Software Development Plan.md glossary/s-z.md#software-development-plan +https://tarf.co.uk/Glossary/s/Software%20Engineering%20Body%20of%20Knowledge/ Glossary/s/Software Engineering Body of Knowledge.md glossary/s-z.md#software-engineering-body-of-knowledge +https://tarf.co.uk/Glossary/s/Software%20Engineering%20Lab/ Glossary/s/Software Engineering Lab.md glossary/s-z.md#software-engineering-lab +https://tarf.co.uk/Glossary/s/Software%20Engineering%20Process%20Group/ Glossary/s/Software Engineering Process Group.md glossary/s-z.md#software-engineering-process-group +https://tarf.co.uk/Glossary/s/Software%20Requirements%20Specification/ Glossary/s/Software Requirements Specification.md glossary/s-z.md#software-requirements-specification +https://tarf.co.uk/Glossary/s/SoGEA/ Glossary/s/SoGEA.md glossary/s-z.md#sogea +https://tarf.co.uk/Glossary/s/SONET/ Glossary/s/SONET.md glossary/s-z.md#sonet +https://tarf.co.uk/Glossary/s/Source%20Code/ Glossary/s/Source Code.md glossary/s-z.md#source-code +https://tarf.co.uk/Glossary/s/SPEEX/ Glossary/s/SPEEX.md glossary/s-z.md#speex +https://tarf.co.uk/Glossary/s/SPI/ Glossary/s/SPI.md glossary/s-z.md#spi +https://tarf.co.uk/Glossary/s/Spiral%20Lifecycle/ Glossary/s/Spiral Lifecycle.md glossary/s-z.md#spiral-lifecycle +https://tarf.co.uk/Glossary/s/Sponsor/ Glossary/s/Sponsor.md glossary/s-z.md#sponsor +https://tarf.co.uk/Glossary/s/Sprial%20Model/ Glossary/s/Sprial Model.md glossary/s-z.md#spiral-model renamed to "Spiral Model" +https://tarf.co.uk/Glossary/s/Sprint%20Planning/ Glossary/s/Sprint Planning.md glossary/s-z.md#sprint-planning +https://tarf.co.uk/Glossary/s/Sprint%20retrospective/ Glossary/s/Sprint retrospective.md glossary/s-z.md#sprint-retrospective +https://tarf.co.uk/Glossary/s/Sprints/ Glossary/s/Sprints.md glossary/s-z.md#sprints +https://tarf.co.uk/Glossary/s/SQL/ Glossary/s/SQL.md glossary/s-z.md#sql +https://tarf.co.uk/Glossary/s/SS7/ Glossary/s/SS7.md glossary/s-z.md#ss7 +https://tarf.co.uk/Glossary/s/SSADM/ Glossary/s/SSADM.md glossary/s-z.md#ssadm +https://tarf.co.uk/Glossary/s/SSH/ Glossary/s/SSH.md glossary/s-z.md#ssh +https://tarf.co.uk/Glossary/s/SSID/ Glossary/s/SSID.md glossary/s-z.md#ssid +https://tarf.co.uk/Glossary/s/SSIS/ Glossary/s/SSIS.md glossary/s-z.md#ssis +https://tarf.co.uk/Glossary/s/SSL/ Glossary/s/SSL.md glossary/s-z.md#ssl +https://tarf.co.uk/Glossary/s/Stack/ Glossary/s/Stack.md glossary/s-z.md#stack +https://tarf.co.uk/Glossary/s/Staff%20Days/ Glossary/s/Staff Days.md glossary/s-z.md#staff-days +https://tarf.co.uk/Glossary/s/Stage/ Glossary/s/Stage.md glossary/s-z.md#stage +https://tarf.co.uk/Glossary/s/Staged%20Delivery%20Lifecycle/ Glossary/s/Staged Delivery Lifecycle.md glossary/s-z.md#staged-delivery-lifecycle +https://tarf.co.uk/Glossary/s/Stakeholder/ Glossary/s/Stakeholder.md glossary/s-z.md#stakeholder +https://tarf.co.uk/Glossary/s/Standard/ Glossary/s/Standard.md glossary/s-z.md#standard +https://tarf.co.uk/Glossary/s/Statistical%20Estimation/ Glossary/s/Statistical Estimation.md glossary/s-z.md#statistical-estimation +https://tarf.co.uk/Glossary/s/STB/ Glossary/s/STB.md glossary/s-z.md#stb +https://tarf.co.uk/Glossary/s/Story%20Mapping/ Glossary/s/Story Mapping.md glossary/s-z.md#story-mapping +https://tarf.co.uk/Glossary/s/Story%20Splitting/ Glossary/s/Story Splitting.md glossary/s-z.md#story-splitting +https://tarf.co.uk/Glossary/s/Storyboard/ Glossary/s/Storyboard.md glossary/s-z.md#storyboard +https://tarf.co.uk/Glossary/s/STP/ Glossary/s/STP.md glossary/s-z.md#stp +https://tarf.co.uk/Glossary/s/Strategy/ Glossary/s/Strategy.md glossary/s-z.md#strategy +https://tarf.co.uk/Glossary/s/STUN/ Glossary/s/STUN.md glossary/s-z.md#stun +https://tarf.co.uk/Glossary/s/Subversion/ Glossary/s/Subversion.md glossary/s-z.md#subversion +https://tarf.co.uk/Glossary/s/Sustainable%20Pace/ Glossary/s/Sustainable Pace.md glossary/s-z.md#sustainable-pace +https://tarf.co.uk/Glossary/s/SVC/ Glossary/s/SVC.md glossary/s-z.md#svc +https://tarf.co.uk/Glossary/s/Swift/ Glossary/s/Swift.md glossary/s-z.md#swift +https://tarf.co.uk/Glossary/s/Switch/ Glossary/s/Switch.md glossary/s-z.md#switch +https://tarf.co.uk/Glossary/s/System%20Test%20Environment/ Glossary/s/System Test Environment.md glossary/s-z.md#system-test-environment +https://tarf.co.uk/Glossary/s/System%20Test/ Glossary/s/System Test.md glossary/s-z.md#system-test +https://tarf.co.uk/Glossary/s/System/ Glossary/s/System.md glossary/s-z.md#system +https://tarf.co.uk/Glossary/s/SystemX/ Glossary/s/SystemX.md glossary/s-z.md#systemx +https://tarf.co.uk/Glossary/t/T-Shirt%20Sizing/ Glossary/t/T-Shirt Sizing.md glossary/s-z.md#t-shirt-sizing +https://tarf.co.uk/Glossary/t/t/ Glossary/t/t.md glossary/s-z.md letter index +https://tarf.co.uk/Glossary/t/Task%20Board/ Glossary/t/Task Board.md glossary/s-z.md#task-board +https://tarf.co.uk/Glossary/t/Task%20Estimate/ Glossary/t/Task Estimate.md glossary/s-z.md#task-estimate +https://tarf.co.uk/Glossary/t/Task/ Glossary/t/Task.md glossary/s-z.md#task +https://tarf.co.uk/Glossary/t/TCAP/ Glossary/t/TCAP.md glossary/s-z.md#tcap +https://tarf.co.uk/Glossary/t/Tcl-tk/ Glossary/t/Tcl-tk.md glossary/s-z.md#tcltk renamed to "Tcl/tk" +https://tarf.co.uk/Glossary/t/TCP/ Glossary/t/TCP.md glossary/s-z.md#tcp +https://tarf.co.uk/Glossary/t/Tcsh/ Glossary/t/Tcsh.md glossary/s-z.md#tcsh +https://tarf.co.uk/Glossary/t/TDD/ Glossary/t/TDD.md glossary/s-z.md#tdd +https://tarf.co.uk/Glossary/t/TDM/ Glossary/t/TDM.md glossary/s-z.md#tdm +https://tarf.co.uk/Glossary/t/Team%20Room/ Glossary/t/Team Room.md glossary/s-z.md#team-room +https://tarf.co.uk/Glossary/t/Team/ Glossary/t/Team.md glossary/s-z.md#team +https://tarf.co.uk/Glossary/t/Technical%20Debt/ Glossary/t/Technical Debt.md glossary/s-z.md#technical-debt +https://tarf.co.uk/Glossary/t/Template/ Glossary/t/Template.md glossary/s-z.md#template +https://tarf.co.uk/Glossary/t/Test%20Activity/ Glossary/t/Test Activity.md glossary/s-z.md#test-activity +https://tarf.co.uk/Glossary/t/Test%20Case%20Specification/ Glossary/t/Test Case Specification.md glossary/s-z.md#test-case-specification +https://tarf.co.uk/Glossary/t/Test%20Case/ Glossary/t/Test Case.md glossary/s-z.md#test-case +https://tarf.co.uk/Glossary/t/Test%20Design%20Specification/ Glossary/t/Test Design Specification.md glossary/s-z.md#test-design-specification +https://tarf.co.uk/Glossary/t/Test%20Design/ Glossary/t/Test Design.md glossary/s-z.md#test-design +https://tarf.co.uk/Glossary/t/Test%20Level/ Glossary/t/Test Level.md glossary/s-z.md#test-level +https://tarf.co.uk/Glossary/t/Test%20Plan/ Glossary/t/Test Plan.md glossary/s-z.md#test-plan +https://tarf.co.uk/Glossary/t/Test%20Technique/ Glossary/t/Test Technique.md glossary/s-z.md#test-technique +https://tarf.co.uk/Glossary/t/Test%20Type/ Glossary/t/Test Type.md glossary/s-z.md#test-type +https://tarf.co.uk/Glossary/t/Test/ Glossary/t/Test.md glossary/s-z.md#test +https://tarf.co.uk/Glossary/t/Testing/ Glossary/t/Testing.md glossary/s-z.md#testing +https://tarf.co.uk/Glossary/t/Three%20Amigos/ Glossary/t/Three Amigos.md glossary/s-z.md#three-amigos +https://tarf.co.uk/Glossary/t/Three%20C%27s/ Glossary/t/Three C's.md glossary/s-z.md#three-cs +https://tarf.co.uk/Glossary/t/Three%20Questions/ Glossary/t/Three Questions.md glossary/s-z.md#three-questions +https://tarf.co.uk/Glossary/t/TIA/ Glossary/t/TIA.md glossary/s-z.md#tia +https://tarf.co.uk/Glossary/t/Timebox/ Glossary/t/Timebox.md glossary/s-z.md#timebox +https://tarf.co.uk/Glossary/t/TKIP/ Glossary/t/TKIP.md glossary/s-z.md#tkip +https://tarf.co.uk/Glossary/t/TLS/ Glossary/t/TLS.md glossary/s-z.md#tls +https://tarf.co.uk/Glossary/t/TLV/ Glossary/t/TLV.md glossary/s-z.md#tlv +https://tarf.co.uk/Glossary/t/Token%20Ring/ Glossary/t/Token Ring.md glossary/s-z.md#token-ring +https://tarf.co.uk/Glossary/t/TOML/ Glossary/t/TOML.md glossary/s-z.md#toml +https://tarf.co.uk/Glossary/t/Top%20Level%20Schedule/ Glossary/t/Top Level Schedule.md glossary/s-z.md#top-level-schedule +https://tarf.co.uk/Glossary/t/Top-Down%20Estimation/ Glossary/t/Top-Down Estimation.md glossary/s-z.md#top-down-estimation +https://tarf.co.uk/Glossary/t/Triple%20DES/ Glossary/t/Triple DES.md glossary/s-z.md#triple-des +https://tarf.co.uk/Glossary/t/TTY/ Glossary/t/TTY.md glossary/s-z.md#tty +https://tarf.co.uk/Glossary/t/TUP/ Glossary/t/TUP.md glossary/s-z.md#tup +https://tarf.co.uk/Glossary/t/Twisted%20pair/ Glossary/t/Twisted pair.md glossary/s-z.md#twisted-pair +https://tarf.co.uk/Glossary/u/u/ Glossary/u/u.md glossary/s-z.md letter index +https://tarf.co.uk/Glossary/u/UA/ Glossary/u/UA.md glossary/s-z.md#ua +https://tarf.co.uk/Glossary/u/Ubiquitous%20Language/ Glossary/u/Ubiquitous Language.md glossary/s-z.md#ubiquitous-language +https://tarf.co.uk/Glossary/u/UDP/ Glossary/u/UDP.md glossary/s-z.md#udp +https://tarf.co.uk/Glossary/u/UER/ Glossary/u/UER.md glossary/s-z.md#uer +https://tarf.co.uk/Glossary/u/UML/ Glossary/u/UML.md glossary/s-z.md#uml +https://tarf.co.uk/Glossary/u/UMTS/ Glossary/u/UMTS.md glossary/s-z.md#umts +https://tarf.co.uk/Glossary/u/UNI/ Glossary/u/UNI.md glossary/s-z.md#uni +https://tarf.co.uk/Glossary/u/unicast/ Glossary/u/unicast.md glossary/s-z.md#unicast +https://tarf.co.uk/Glossary/u/Unicode/ Glossary/u/Unicode.md glossary/s-z.md#unicode +https://tarf.co.uk/Glossary/u/Unified%20Communications/ Glossary/u/Unified Communications.md glossary/s-z.md#unified-communications +https://tarf.co.uk/Glossary/u/Unified%20Modeling%20Language/ Glossary/u/Unified Modeling Language.md glossary/s-z.md#uml renamed to "UML" +https://tarf.co.uk/Glossary/u/Unit%20Test/ Glossary/u/Unit Test.md glossary/s-z.md#unit-test +https://tarf.co.uk/Glossary/u/Unit%20Testing/ Glossary/u/Unit Testing.md glossary/s-z.md#unit-testing +https://tarf.co.uk/Glossary/u/Unix/ Glossary/u/Unix.md glossary/s-z.md#unix +https://tarf.co.uk/Glossary/u/Update/ Glossary/u/Update.md glossary/s-z.md#update +https://tarf.co.uk/Glossary/u/Upstream/ Glossary/u/Upstream.md glossary/s-z.md#upstream +https://tarf.co.uk/Glossary/u/URI/ Glossary/u/URI.md glossary/s-z.md#uri +https://tarf.co.uk/Glossary/u/URL/ Glossary/u/URL.md glossary/s-z.md#url +https://tarf.co.uk/Glossary/u/URN/ Glossary/u/URN.md glossary/s-z.md#urn +https://tarf.co.uk/Glossary/u/Usability%20Testing/ Glossary/u/Usability Testing.md glossary/s-z.md#usability-testing +https://tarf.co.uk/Glossary/u/Use%20Case%20Model/ Glossary/u/Use Case Model.md glossary/s-z.md#use-case-model +https://tarf.co.uk/Glossary/u/Use%20Case%20Specification/ Glossary/u/Use Case Specification.md glossary/s-z.md#use-case-specification +https://tarf.co.uk/Glossary/u/Use%20Case/ Glossary/u/Use Case.md glossary/s-z.md#use-case +https://tarf.co.uk/Glossary/u/User%20Experience/ Glossary/u/User Experience.md glossary/s-z.md#user-experience +https://tarf.co.uk/Glossary/u/User%20Interface%20Design/ Glossary/u/User Interface Design.md glossary/s-z.md#user-interface-design +https://tarf.co.uk/Glossary/u/User%20Interface%20Prototype/ Glossary/u/User Interface Prototype.md glossary/s-z.md#user-interface-prototype +https://tarf.co.uk/Glossary/u/User%20Interface/ Glossary/u/User Interface.md glossary/s-z.md#user-interface +https://tarf.co.uk/Glossary/u/User%20Plane/ Glossary/u/User Plane.md glossary/s-z.md#user-plane +https://tarf.co.uk/Glossary/u/User%20Stories/ Glossary/u/User Stories.md glossary/s-z.md#user-stories +https://tarf.co.uk/Glossary/u/UTC/ Glossary/u/UTC.md glossary/s-z.md#utc +https://tarf.co.uk/Glossary/u/UTF-16/ Glossary/u/UTF-16.md glossary/s-z.md#utf-16 +https://tarf.co.uk/Glossary/u/UTF-8/ Glossary/u/UTF-8.md glossary/s-z.md#utf-8 +https://tarf.co.uk/Glossary/u/UTRAN/ Glossary/u/UTRAN.md glossary/s-z.md#utran +https://tarf.co.uk/Glossary/v/V%20Model/ Glossary/v/V Model.md glossary/s-z.md#v-model +https://tarf.co.uk/Glossary/v/V.90/ Glossary/v/V.90.md glossary/s-z.md#v90 +https://tarf.co.uk/Glossary/v/V.92/ Glossary/v/V.92.md glossary/s-z.md#v92 +https://tarf.co.uk/Glossary/v/v/ Glossary/v/v.md glossary/s-z.md letter index +https://tarf.co.uk/Glossary/v/VAD/ Glossary/v/VAD.md glossary/s-z.md#vad +https://tarf.co.uk/Glossary/v/VB/ Glossary/v/VB.md glossary/s-z.md#vb +https://tarf.co.uk/Glossary/v/VBS/ Glossary/v/VBS.md glossary/s-z.md#vbs +https://tarf.co.uk/Glossary/v/VC/ Glossary/v/VC.md glossary/s-z.md#vc +https://tarf.co.uk/Glossary/v/VCI/ Glossary/v/VCI.md glossary/s-z.md#vci +https://tarf.co.uk/Glossary/v/VCID/ Glossary/v/VCID.md glossary/s-z.md#vcid +https://tarf.co.uk/Glossary/v/VDSL/ Glossary/v/VDSL.md glossary/s-z.md#vdsl +https://tarf.co.uk/Glossary/v/Velocity/ Glossary/v/Velocity.md glossary/s-z.md#velocity +https://tarf.co.uk/Glossary/v/Verifier/ Glossary/v/Verifier.md glossary/s-z.md#verifier +https://tarf.co.uk/Glossary/v/Version%20Control/ Glossary/v/Version Control.md glossary/s-z.md#version-control +https://tarf.co.uk/Glossary/v/Version/ Glossary/v/Version.md glossary/s-z.md#version +https://tarf.co.uk/Glossary/v/VHDL/ Glossary/v/VHDL.md glossary/s-z.md#vhdl +https://tarf.co.uk/Glossary/v/VISP/ Glossary/v/VISP.md glossary/s-z.md#visp +https://tarf.co.uk/Glossary/v/VLAN/ Glossary/v/VLAN.md glossary/s-z.md#vlan +https://tarf.co.uk/Glossary/v/VLR/ Glossary/v/VLR.md glossary/s-z.md#vlr +https://tarf.co.uk/Glossary/v/VM/ Glossary/v/VM.md glossary/s-z.md#vm +https://tarf.co.uk/Glossary/v/VOD/ Glossary/v/VOD.md glossary/s-z.md#vod +https://tarf.co.uk/Glossary/v/VoIP/ Glossary/v/VoIP.md glossary/s-z.md#voip +https://tarf.co.uk/Glossary/v/VoLTE/ Glossary/v/VoLTE.md glossary/s-z.md#volte +https://tarf.co.uk/Glossary/v/Vorbis/ Glossary/v/Vorbis.md glossary/s-z.md#vorbis +https://tarf.co.uk/Glossary/v/VPI/ Glossary/v/VPI.md glossary/s-z.md#vpi +https://tarf.co.uk/Glossary/v/VPLS/ Glossary/v/VPLS.md glossary/s-z.md#vpls +https://tarf.co.uk/Glossary/v/VPN/ Glossary/v/VPN.md glossary/s-z.md#vpn +https://tarf.co.uk/Glossary/v/VPWS/ Glossary/v/VPWS.md glossary/s-z.md#vpws +https://tarf.co.uk/Glossary/v/VRF/ Glossary/v/VRF.md glossary/s-z.md#vrf +https://tarf.co.uk/Glossary/w/W-CDMA/ Glossary/w/W-CDMA.md glossary/s-z.md#w-cdma +https://tarf.co.uk/Glossary/w/w/ Glossary/w/w.md glossary/s-z.md letter index +https://tarf.co.uk/Glossary/w/W3C/ Glossary/w/W3C.md glossary/s-z.md#w3c +https://tarf.co.uk/Glossary/w/Walkthrough/ Glossary/w/Walkthrough.md glossary/s-z.md#walkthrough +https://tarf.co.uk/Glossary/w/WAN/ Glossary/w/WAN.md glossary/s-z.md#wan +https://tarf.co.uk/Glossary/w/WANET/ Glossary/w/WANET.md glossary/s-z.md#wanet +https://tarf.co.uk/Glossary/w/WAP/ Glossary/w/WAP.md glossary/s-z.md#wap +https://tarf.co.uk/Glossary/w/Waterfall%20Lifecycle/ Glossary/w/Waterfall Lifecycle.md glossary/s-z.md#waterfall-lifecycle +https://tarf.co.uk/Glossary/w/Waterfall/ Glossary/w/Waterfall.md glossary/s-z.md#waterfall +https://tarf.co.uk/Glossary/w/WBC/ Glossary/w/WBC.md glossary/s-z.md#wbc +https://tarf.co.uk/Glossary/w/WBCC/ Glossary/w/WBCC.md glossary/s-z.md#wbcc +https://tarf.co.uk/Glossary/w/WBMC/ Glossary/w/WBMC.md glossary/s-z.md#wbmc +https://tarf.co.uk/Glossary/w/Weekly%20Individual%20Plan/ Glossary/w/Weekly Individual Plan.md glossary/s-z.md#weekly-individual-plan +https://tarf.co.uk/Glossary/w/WEP/ Glossary/w/WEP.md glossary/s-z.md#wep +https://tarf.co.uk/Glossary/w/What%20Requirement/ Glossary/w/What Requirement.md glossary/s-z.md#what-requirement +https://tarf.co.uk/Glossary/w/Why%20Requirement/ Glossary/w/Why Requirement.md glossary/s-z.md#why-requirement +https://tarf.co.uk/Glossary/w/Wi-Fi/ Glossary/w/Wi-Fi.md glossary/s-z.md#wi-fi +https://tarf.co.uk/Glossary/w/Wiki/ Glossary/w/Wiki.md glossary/s-z.md#wiki +https://tarf.co.uk/Glossary/w/WiMAX/ Glossary/w/WiMAX.md glossary/s-z.md#wimax +https://tarf.co.uk/Glossary/w/WIN-T/ Glossary/w/WIN-T.md glossary/s-z.md#win-t +https://tarf.co.uk/Glossary/w/Wireless%20Mesh%20Network/ Glossary/w/Wireless Mesh Network.md glossary/s-z.md#wireless-mesh-network +https://tarf.co.uk/Glossary/w/Wireless%20Repeater/ Glossary/w/Wireless Repeater.md glossary/s-z.md#wireless-repeater +https://tarf.co.uk/Glossary/w/Wireshark/ Glossary/w/Wireshark.md glossary/s-z.md#wireshark +https://tarf.co.uk/Glossary/w/WISP/ Glossary/w/WISP.md glossary/s-z.md#wisp +https://tarf.co.uk/Glossary/w/WLR/ Glossary/w/WLR.md glossary/s-z.md#wlr +https://tarf.co.uk/Glossary/w/WMA/ Glossary/w/WMA.md glossary/s-z.md#wma +https://tarf.co.uk/Glossary/w/Work%20Breakdown%20Structure/ Glossary/w/Work Breakdown Structure.md glossary/s-z.md#work-breakdown-structure +https://tarf.co.uk/Glossary/w/Work%20Item/ Glossary/w/Work Item.md glossary/s-z.md#work-item +https://tarf.co.uk/Glossary/w/Work%20Package/ Glossary/w/Work Package.md glossary/s-z.md#work-package +https://tarf.co.uk/Glossary/w/Work%20Plan/ Glossary/w/Work Plan.md glossary/s-z.md#work-plan +https://tarf.co.uk/Glossary/w/Work%20Product/ Glossary/w/Work Product.md glossary/s-z.md#work-product +https://tarf.co.uk/Glossary/w/WPA2/ Glossary/w/WPA2.md glossary/s-z.md#wpa2 +https://tarf.co.uk/Glossary/w/WPS/ Glossary/w/WPS.md glossary/s-z.md#wps +https://tarf.co.uk/Glossary/w/write-only%20code/ Glossary/w/write-only code.md glossary/s-z.md#write-only-code +https://tarf.co.uk/Glossary/w/WS-BPEL/ Glossary/w/WS-BPEL.md glossary/s-z.md#ws-bpel +https://tarf.co.uk/Glossary/w/WSDL/ Glossary/w/WSDL.md glossary/s-z.md#wsdl +https://tarf.co.uk/Glossary/x/X.25/ Glossary/x/X.25.md glossary/s-z.md#x25 +https://tarf.co.uk/Glossary/x/X.509/ Glossary/x/X.509.md glossary/s-z.md#x509 +https://tarf.co.uk/Glossary/x/x/ Glossary/x/x.md glossary/s-z.md letter index +https://tarf.co.uk/Glossary/x/XML%20Schema/ Glossary/x/XML Schema.md glossary/s-z.md#xml-schema +https://tarf.co.uk/Glossary/x/XML-RPC/ Glossary/x/XML-RPC.md glossary/s-z.md#xml-rpc +https://tarf.co.uk/Glossary/x/XML/ Glossary/x/XML.md glossary/s-z.md#xml +https://tarf.co.uk/Glossary/x/XMPP/ Glossary/x/XMPP.md glossary/s-z.md#xmpp +https://tarf.co.uk/Glossary/x/XP/ Glossary/x/XP.md glossary/s-z.md#xp +https://tarf.co.uk/Glossary/x/xsd/ Glossary/x/xsd.md glossary/s-z.md#xsd +https://tarf.co.uk/Glossary/x/XSS/ Glossary/x/XSS.md glossary/s-z.md#xss +https://tarf.co.uk/Glossary/y/y/ Glossary/y/y.md glossary/s-z.md letter index +https://tarf.co.uk/Glossary/y/YAML/ Glossary/y/YAML.md glossary/s-z.md#yaml +https://tarf.co.uk/Glossary/z/z/ Glossary/z/z.md glossary/s-z.md letter index +https://tarf.co.uk/Glossary/z/ZigBee/ Glossary/z/ZigBee.md glossary/s-z.md#zigbee +https://tarf.co.uk/Glossary/%CE%BC/%CE%BC-law/ Glossary/μ/μ-law.md glossary/l-n.md#mu-law renamed to "Mu-law" +https://tarf.co.uk/Glossary/%CE%BC/%CE%BC/ Glossary/μ/μ.md glossary/s-z.md letter index +https://markbac.github.io/technical-documentation/glossary/ glossary/index.md technical-documentation site; redirect lives in that repository +https://markbac.github.io/technical-documentation/glossary/a-c/ glossary/a-c.md same anchors except the rows below +https://markbac.github.io/technical-documentation/glossary/d-f/ glossary/d-f.md same anchors except the rows 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+https://markbac.github.io/technical-documentation/glossary/a-c/#construx-knowledge-area glossary/s-z.md#software-engineering-body-of-knowledge renamed to "Software Engineering Body of Knowledge" +https://markbac.github.io/technical-documentation/glossary/a-c/#corrective-activity-management glossary/a-c.md dropped +https://markbac.github.io/technical-documentation/glossary/d-f/#data-modeling glossary/d-f.md#data-modelling renamed to "Data modelling" +https://markbac.github.io/technical-documentation/glossary/d-f/#date-warehouse glossary/d-f.md#data-warehouse renamed to "Data Warehouse" +https://markbac.github.io/technical-documentation/glossary/d-f/#deplhi glossary/d-f.md#delphi renamed to "Delphi" +https://markbac.github.io/technical-documentation/glossary/d-f/#eee-8021qay glossary/g-k.md#ieee-8021qay renamed to "IEEE 802.1Qay" +https://markbac.github.io/technical-documentation/glossary/d-f/#evaluation glossary/d-f.md dropped 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a/content/glossary/s-z.md b/content/glossary/s-z.md new file mode 100644 index 0000000..3c40a12 --- /dev/null +++ b/content/glossary/s-z.md @@ -0,0 +1,1379 @@ +--- +title: Glossary, S to Z and numbers +--- + +# S to Z and numbers + +## S + +### S-Tag +**Service VLAN tag.** In IEEE 802.1ad double tagging (Q-in-Q), the outer VLAN tag added by the service provider, with TPID 0x88A8. It sits outside the customer's own C-Tag. + +See also: [C-Tag](a-c.md#c-tag), [VLAN](#vlan), [Dot1Q](d-f.md#dot1q). + +### S-GW +**Serving Gateway.** The LTE core gateway that forwards users' packets between the eNodeBs and the PGW. It anchors the user plane during handovers and buffers data for idle devices while the MME pages them. + +See also: [PGW](o-r.md#pgw), [MME](l-n.md#mme), [LTE (4G)](l-n.md#lte-4g). + +### SAAL +**Signalling ATM Adaptation Layer.** The ATM adaptation layer that carries signalling messages reliably between ATM switches. + +See also: [ATM](a-c.md#atm), [AAL5](a-c.md#aal5). + +### SaaS +**Software as a Service.** Software that a provider hosts and runs, and customers use over the internet, usually in a browser, on a subscription. + +See also: [PaaS](o-r.md#paas), [IaaS](g-k.md#iaas). + +### SAE +**System Architecture Evolution.** The 3GPP work that defined the LTE core network, the Evolved Packet Core: a simpler, all-IP core that also supports other access networks, such as Wi-Fi. + +See also: [LTE (4G)](l-n.md#lte-4g), [MME](l-n.md#mme), [S-GW](#s-gw), [PGW](o-r.md#pgw). + +### SAFe +**Scaled Agile Framework.** A framework for running agile development across many teams in a large organisation, with set roles, planning events and portfolio management. + +See also: [Scaled Agile](#scaled-agile), [LeSS](l-n.md#less), [DAD](d-f.md#dad). + +### SBC +**Session Border Controller.** A device at the edge of a VoIP network that controls the signalling, and usually the media, of calls crossing it. It provides security, NAT traversal, interworking and policing. + +See also: [SIP](#sip), [SIP Trunk](#sip-trunk), [NAT](l-n.md#nat). + +### SC-FDMA +**Single-Carrier FDMA.** A multiple access scheme, also called DFT-spread OFDMA, with a lower peak-to-average power ratio than OFDMA. That saves battery power, so LTE uses it for the uplink. + +See also: [OFDMA](o-r.md#ofdma), [LTE (4G)](l-n.md#lte-4g). + +### Scala +A statically typed language for the Java virtual machine that combines object-oriented and functional programming, and works with Java libraries. + +See also: [Java](g-k.md#java). + +### Scaled Agile +Agile methods applied to large projects and programmes, with many teams working on one product. + +See also: [SAFe](#safe), [LeSS](l-n.md#less), [Scrum of Scrums](#scrum-of-scrums). + +### SCCP +**Signalling Connection Control Part.** The SS7 layer above MTP that adds richer addressing (global title translation), connection-oriented services and segmentation. MAP and other application parts use it. + +See also: [MTP](l-n.md#mtp), [SS7](#ss7), [TCAP](#tcap). + +### Scenario +A narrative of an activity, told as a story, often a concrete path through a use case. + +See also: [Use Case](#use-case), [Storyboard](#storyboard). + +### Schedule +A plan that sets the timing, resources and dependencies of the tasks needed to finish a project or part of one. + +See also: [Business Schedule](a-c.md#business-schedule), [Detailed Schedule](d-f.md#detailed-schedule). + +### Scheduler +The part of an operating system, or a network device, that decides which task or packet gets a resource next, such as a processor or a link. Its aims include keeping resources busy, sharing them fairly and meeting deadlines or quality of service targets. + +See also: [Round Robin](o-r.md#round-robin), [Preemption](o-r.md#preemption), [RTOS](o-r.md#rtos). + +### SCM +**Software Configuration Management.** Tracking and controlling changes to software: version control, baselines, builds and releases. It is the software part of configuration management. + +See also: [Configuration Management](a-c.md#configuration-management), [Version Control](#version-control). + +### Scratch +A visual, block-based programming language and online community from the MIT Media Lab, designed to teach children to code. + +### Scribe +The person who records issues in an inspection or other formal meeting. + +See also: [Inspection](g-k.md#inspection). + +### Scrum +An agile framework in which a small team works in fixed-length sprints towards a sprint goal. It has three roles: product owner, Scrum Master and developers. Its events are sprint planning, the daily scrum, the sprint review and the retrospective. + +See also: [Sprints](#sprints), [Product Owner](o-r.md#product-owner), [Scrum Master](#scrum-master). + +### Scrum Master +The Scrum role that helps the team follow Scrum and work well, by coaching, removing obstacles and protecting the team's focus. + +See also: [Scrum](#scrum). + +### Scrum of Scrums +A way to coordinate several Scrum teams: each team sends a representative to a regular meeting to raise dependencies and problems between teams. + +See also: [Scaled Agile](#scaled-agile). + +### SCTP +**Stream Control Transmission Protocol.** A transport protocol (RFC 9260) that delivers messages reliably like TCP, keeps message boundaries like UDP, and supports multiple streams and multi-homing. It carries SS7 signalling over IP (SIGTRAN) and LTE control traffic. + +See also: [TCP](#tcp), [UDP](#udp), [SGW](#sgw). + +### SDES +**SDP Security Descriptions.** A way to exchange the keys for SRTP (secure RTP) inside the SDP of a SIP call. It relies on the signalling itself being encrypted. + +See also: [SDP](#sdp), [RTP](o-r.md#rtp), [SIP](#sip). + +### SDH +**Synchronous Digital Hierarchy.** The ITU-T standard for synchronous multiplexing of digital signals over fibre, from STM-1 (155 Mbit/s) upwards, with strong management and fast protection switching. It replaced PDH; SONET is the North American equivalent. + +See also: [SONET](#sonet), [PDH](o-r.md#pdh), [EoS](d-f.md#eos). + +### SDK +**Software Development Kit.** The libraries, tools, documentation and examples needed to build software for a particular platform or service. + +See also: [API](a-c.md#api), [DDK](d-f.md#ddk). + +### SDLC +**Systems Development Life Cycle.** A structured process for developing a system, from feasibility study through to maintenance. Waterfall, spiral and iterative models are all versions of it. + +See also: [Lifecycle](l-n.md#lifecycle), [Waterfall](#waterfall). + +### SDMA +**Space-Division Multiple Access.** Using smart antennas to point beams at different users, so that users in different places can share the same frequency at the same time. + +See also: [MIMO](l-n.md#mimo), [CDMA](a-c.md#cdma). + +### SDN +**Software-Defined Networking.** Separating a network's control plane from its data plane, and putting control in software controllers that configure the forwarding devices through open interfaces. The network is then managed centrally and programmatically. + +See also: [Control Plane](a-c.md#control-plane), [Data Plane](d-f.md#data-plane), [NaaS](l-n.md#naas). + +### SDP +**Session Description Protocol.** A text format (RFC 8866) for describing multimedia sessions: media types, codecs, addresses and ports. SIP uses it in an offer and answer exchange to agree the media of a call. + +See also: [SIP](#sip), [SDES](#sdes), [RTP](o-r.md#rtp). + +### SDS +**Software Design Specification.** A document that sets out a system's detailed design: its modules, interfaces, data models, state machines, timing and memory layout. Ideally it is kept up to date alongside the code. + +See also: [Software Requirements Specification](#software-requirements-specification), [Low Level Design](l-n.md#low-level-design). + +### SDSL +**Symmetric Digital Subscriber Line.** DSL with the same speed in both directions, aimed at businesses. HDSL and G.SHDSL are examples. + +See also: [ADSL](a-c.md#adsl), [HDSL](g-k.md#hdsl), [DSL](d-f.md#dsl). + +### Sed +**Stream editor.** A Unix tool, written at Bell Labs in the 1970s, that transforms text line by line using a small command language, most often for substitutions with regular expressions. + +See also: [Awk](a-c.md#awk), [Regular expression](o-r.md#regular-expression). + +### Secure Element +**SE.** A tamper-resistant chip that stores keys and runs sensitive code in isolation, with protection against physical and side-channel attacks. SIM cards, payment cards and many IoT devices use one. + +See also: [Root of Trust](o-r.md#root-of-trust), [TrustZone](#trustzone), [SIM](#sim). + +### SE +See [Secure Element](#secure-element). + +### Semaphore +A synchronisation primitive: a counter that threads decrement to take one unit of a resource, waiting if none is left, and increment to release it. A binary semaphore works like a lock. + +See also: [Mutex](l-n.md#mutex), [Mutual Exclusion](l-n.md#mutual-exclusion). + +### Semantic Versioning +**SemVer.** A version numbering scheme, `MAJOR.MINOR.PATCH`. Increase the major number for incompatible API changes, the minor number for compatible new features and the patch number for compatible bug fixes. Pre-release and build labels can follow, as in `2.1.0-rc.1+build.5`. + +See also: [Release Management](o-r.md#release-management), [Version](#version). + +### Sequence Model +A model, such as a UML sequence diagram, that shows the messages exchanged between objects or roles in time order. + +See also: [Collaboration Model](a-c.md#collaboration-model), [UML](#uml). + +### SF +**Superframe.** The T1 framing format that groups 12 frames and uses their framing bits for alignment. Extended Superframe (ESF), with 24 frames, replaced it. + +See also: [PDH](o-r.md#pdh), [TDM](#tdm). + +### SFTP +**SSH File Transfer Protocol.** A protocol for transferring and managing files over an SSH connection. It is unrelated to FTP and FTPS, apart from its purpose. + +See also: [SSH](#ssh), [FTPS](d-f.md#ftps), [FTP](d-f.md#ftp). + +### SGML +**Standard Generalized Markup Language.** The ISO standard (ISO 8879) for defining markup languages that describe a document's structure rather than its appearance. HTML and XML derive from it. + +See also: [XML](#xml). + +### SGSN +**Serving GPRS Support Node.** The GPRS and UMTS core node that serves devices in its area. It tracks their location, authenticates them and routes their packets to and from the GGSN. + +See also: [GGSN](g-k.md#ggsn), [GPRS](g-k.md#gprs), [MME](l-n.md#mme). + +### SGW +**Signalling Gateway.** A gateway that carries SS7 signalling between circuit-switched networks and IP networks, for example passing ISUP from an MGCF over SCTP (SIGTRAN) to the SS7 network over MTP. + +See also: [MGCF](l-n.md#mgcf), [SCTP](#sctp), [SS7](#ss7). + +### Sh +The Bourne shell, the standard shell of Version 7 Unix, written by Stephen Bourne. `/bin/sh` on Unix-like systems today is a shell compatible with it, as POSIX defines. + +See also: [Bash](a-c.md#bash), [Ksh](g-k.md#ksh), [Shell Scripting](#shell-scripting), [POSIX](o-r.md#posix). + +### SHA +**Secure Hash Algorithm.** A family of cryptographic hash functions published by NIST. SHA-1 (160-bit) is broken and should not be used for security. SHA-2 (SHA-256, SHA-512) and SHA-3 are current. + +See also: [Hash Function](g-k.md#hash-function), [MD5](l-n.md#md5). + +### Shell Scripting +Writing scripts for a command-line shell, such as Bash, to automate tasks like handling files and running other tools. + +See also: [Bash](a-c.md#bash), [Sh](#sh). + +### Sidetone +The small part of a speaker's own voice fed back into their earpiece, so that a phone line sounds alive and people do not shout. + +See also: [Echo](d-f.md#echo). + +### Sign Up +**Signing up for tasks.** In agile teams, members choose the tasks they will work on, rather than a manager assigning them. + +See also: [Task Board](#task-board). + +### SIM +**Subscriber Identity Module.** The smart card, or embedded chip (eSIM), that holds a mobile subscriber's IMSI and secret key. The network uses them to identify and authenticate the subscriber. + +See also: [IMSI](g-k.md#imsi), [Secure Element](#secure-element), [HLR](g-k.md#hlr). + +### SIMPLE +**SIP for Instant Messaging and Presence Leveraging Extensions.** The IETF's SIP-based protocols for instant messaging and presence. XMPP is the main alternative. + +See also: [SIP](#sip), [XMPP](#xmpp). + +### Simple Design +The agile practice of keeping the design as simple as the current needs allow, guided by rules such as Kent Beck's. + +See also: [Rule of Simplicity](o-r.md#rule-of-simplicity), [KISS Principle](g-k.md#kiss-principle), [Quick Design Session](o-r.md#quick-design-session). + +### Simplex +Communication in one direction only, such as broadcast radio. ITU usage also applies the term to links that work one way at a time, which most people call half duplex. + +See also: [Duplex](d-f.md#duplex), [Half Duplex](g-k.md#half-duplex). + +### Single Step Test +A test in a debugger, stepping through the source code line by line as it runs. + +### SIP +**Session Initiation Protocol.** The IETF's text-based signalling protocol (RFC 3261) for setting up, changing and ending voice, video and messaging sessions. It is modelled on HTTP and carries SDP to agree the media. SIP is the basis of most VoIP and of IMS. + +See also: [SDP](#sdp), [RTP](o-r.md#rtp), [IMS](g-k.md#ims), [SIP Trunk](#sip-trunk). + +### SIP Trunk +A VoIP connection, using SIP, between a business's phone system and a service provider, replacing ISDN lines for external calls. + +See also: [SIP](#sip), [SBC](#sbc), [ISDN](g-k.md#isdn). + +### SISO +**Single-Input, Single-Output.** A system with one input and one output; in radio, a link with one antenna at each end. + +See also: [MIMO](l-n.md#mimo). + +### Skew +**Clock skew.** The difference in the arrival time of the same clock signal at different parts of a circuit, or between the readings of two clocks. + +See also: [Jitter](g-k.md#jitter). + +### SLA +**Service Level Agreement.** An agreement between a provider and a customer on the service's measurable levels, such as availability, response and repair times, with remedies if they are missed. + +See also: [KPI](g-k.md#kpi), [MTR](l-n.md#mtr). + +### SLIP +**Serial Line Internet Protocol.** A very simple way of sending IP packets over a serial line (RFC 1055), with no negotiation or error checking. PPP replaced it, though it is still used on small microcontrollers. + +See also: [PPP](o-r.md#ppp). + +### SME +**Subject Matter Expert.** A person with deep knowledge of a particular area, often a business domain that the software serves. SME also commonly means small and medium-sized enterprise. + +### Smoke Test +A quick test that a new build works at all, run before deeper testing. + +See also: [Smoke testing](#smoke-testing), [Build](a-c.md#build). + +### Smoke testing +Quick, shallow testing of a system's most important functions, to decide whether it is stable enough for further testing. + +See also: [Smoke Test](#smoke-test), [Regression testing](o-r.md#regression-testing). + +### SMP +**Symmetric Multiprocessing.** A design in which two or more identical processors, or cores, share one memory and are run by one operating system that treats them all equally. Most multi-core computers work this way. + +See also: [AMP](a-c.md#amp). + +### SMPF +**Shared Metallic Path Facility.** An Openreach product that shares one copper line between two providers. Typically one provides voice over the low frequencies and the other broadband over the high frequencies. + +See also: [MPF](l-n.md#mpf), [WLR](#wlr). + +### SMSC +**Short Message Service Centre.** The network element that stores SMS messages and forwards them to their destination, retrying until the recipient is reachable. + +See also: [MAP](l-n.md#map), [GSM](g-k.md#gsm). + +### Snake Case +Writing compound names in lower case with underscores between the words, as in `snake_case`. Python uses it for functions and variables. + +See also: [Camel Case](a-c.md#camel-case). + +### SNMP +**Simple Network Management Protocol.** The IETF protocol for monitoring and managing network devices. Managers read and set variables in each device's MIB, and devices send traps when events happen. SNMPv3 adds proper security. + +See also: [MIB](l-n.md#mib), [Management Plane](l-n.md#management-plane), [Cacti](a-c.md#cacti). + +### SNTP +**Simple Network Time Protocol.** A simpler form of NTP, without NTP's long-term state and filtering, for devices that need only modest clock accuracy. + +See also: [NTP](l-n.md#ntp). + +### SOA +**Service-Oriented Architecture.** An architecture style in which applications are built from services. Each service provides a business function through a network interface, can be used without knowing how it works, and can be combined with others. + +See also: [ESB](d-f.md#esb), [Microservice](l-n.md#microservice), [SOAP](#soap). + +### SOAP +An XML-based messaging protocol for web services, usually over HTTP. A SOAP envelope holds a header and a body, and WSDL describes the services. REST has largely replaced it for new APIs. + +See also: [WSDL](#wsdl), [REST](o-r.md#rest), [XML](#xml). + +### Softswitch +A call control system implemented in software on general-purpose servers, which routes calls in VoIP and next-generation networks. It controls media gateways rather than switching media itself. + +See also: [Class 4 Softswitch](a-c.md#class-4-softswitch), [Class 5 Softswitch](a-c.md#class-5-softswitch), [MGCP](l-n.md#mgcp), [H.248](g-k.md#h248). + +### Software Change Request +See [Change Request](a-c.md#change-request). + +### Software Configuration Management +See [SCM](#scm). + +### Software Development Plan +**SDP.** On software projects, another name for the [Project Plan](o-r.md#project-plan). + +### Software Engineering Body of Knowledge +**SWEBOK.** The IEEE Computer Society's guide to the generally accepted knowledge of software engineering, organised into knowledge areas. + +See also: [IEEE](g-k.md#ieee). + +### Software Engineering Lab +**SEL.** The Software Engineering Laboratory at NASA Goddard, which studied and improved software processes from 1976 into the 2000s. + +### Software Engineering Process Group +**SEPG.** A group that leads software process improvement in an organisation, and gives projects independent technical oversight. + +See also: [Capability Maturity Model](a-c.md#capability-maturity-model). + +### Software Requirements Specification +**SRS.** A document that captures the requirements for a software system, often alongside models and prototypes. + +See also: [Requirements](o-r.md#requirements), [SDS](#sds). + +### SOLID Principles +Five object-oriented design principles promoted by Robert C. Martin: single responsibility, open-closed, Liskov substitution, interface segregation and dependency inversion. Together they aim for code that is modular and easy to change. + +See also: [OO](o-r.md#oo), [Design Pattern](d-f.md#design-pattern). + +### SoGEA +**Single Order Generic Ethernet Access.** An Openreach broadband product over fibre to the cabinet with no phone service on the line, ordered as one product. It is the standalone broadband line used as the copper phone network closes. + +See also: [VDSL](#vdsl), [EoFTTC](d-f.md#eofttc), [PSTN](o-r.md#pstn). + +### SONET +**Synchronous Optical Network.** The North American standard for synchronous multiplexing over fibre, equivalent to SDH, with rates starting at OC-1 (51.84 Mbit/s). + +See also: [SDH](#sdh). + +### Source Code +The human-readable instructions of software, written in a programming language, that a compiler or interpreter turns into something a computer can run. + +See also: [Machine code](l-n.md#machine-code), [Version Control](#version-control). + +### SPEEX +**Speex.** An open, patent-free speech codec from the Xiph.Org Foundation, based on CELP. Opus has replaced it. + +See also: [OPUS](o-r.md#opus), [Vorbis](#vorbis). + +### SPI +**Serial Peripheral Interface.** A synchronous, full-duplex serial bus for short-distance links between a microcontroller and peripherals such as sensors, flash memory and displays. It uses a clock, two data lines and a chip select for each device. + +See also: [MCU](l-n.md#mcu). + +### Spiral Lifecycle +A lifecycle made of a series of small projects, each tackling the biggest remaining risks, until the system is delivered. + +See also: [Spiral Model](#spiral-model), [Lifecycle](l-n.md#lifecycle). + +### Sponsor +See [Project Sponsor](o-r.md#project-sponsor). + +### Spiral Model +Barry Boehm's risk-driven process model. Each loop of the spiral sets objectives, identifies and resolves risks, develops and tests, and plans the next loop. It can borrow from other models, such as waterfall or prototyping, as the risks suggest. + +See also: [Spiral Lifecycle](#spiral-lifecycle), [Waterfall](#waterfall). + +### Sprint Planning +The Scrum event at the start of a sprint, in which the team agrees the sprint goal and chooses the backlog items to work on. + +See also: [Sprints](#sprints), [Scrum](#scrum). + +### Sprint retrospective +The Scrum event at the end of a sprint, in which the team reviews how it worked and agrees improvements. + +See also: [Heartbeat Retrospective](g-k.md#heartbeat-retrospective), [Scrum](#scrum). + +### Sprints +Fixed-length iterations, usually two to four weeks, in which a Scrum team produces a usable increment. + +See also: [Iteration](g-k.md#iteration), [Timebox](#timebox), [Scrum](#scrum). + +### SQL +**Structured Query Language.** The standard language for defining, querying and changing data in relational databases. + +See also: [RDBMS](o-r.md#rdbms), [NoSQL](l-n.md#nosql). + +### SS7 +**Signalling System No. 7.** The ITU-T set of protocols that telephone networks use to set up and clear calls and to provide services such as number translation, number portability, prepaid and SMS. In the UK it is also called C7. Its layers include MTP, SCCP, TCAP, ISUP and MAP. + +See also: [MTP](l-n.md#mtp), [SCCP](#sccp), [ISUP](g-k.md#isup), [TCAP](#tcap), [MAP](l-n.md#map), [CCS](a-c.md#ccs). + +### SSADM +**Structured Systems Analysis and Design Method.** A waterfall method for analysing and designing information systems, developed for and widely used in UK government from the 1980s. + +See also: [Waterfall](#waterfall), [CCTA](a-c.md#ccta). + +### SSH +**Secure Shell.** A cryptographic protocol for logging in to and running commands on remote machines securely over an untrusted network. It also tunnels other traffic and carries SFTP. + +See also: [SFTP](#sftp). + +### SSID +**Service Set Identifier.** The name of a Wi-Fi network. + +See also: [Wi-Fi](#wi-fi). + +### SSIS +**SQL Server Integration Services.** The Microsoft SQL Server component for data integration and ETL workflows. + +See also: [ETL](d-f.md#etl). + +### SSL +**Secure Sockets Layer.** The predecessor of TLS. All SSL versions are broken and must not be used, though "SSL" is still often said when TLS is meant. See [TLS](#tls). + +### Stack +A protocol stack: the layered set of protocols that together provide communication, such as Ethernet, IP, TCP and HTTP, or the software that implements them. + +```mermaid +flowchart TB + A["HTTP (application)"] --> B["TCP (transport)"] --> C["IP (network)"] --> D["Ethernet (link)"] --> E["Cable (physical)"] +``` + +[[CAPTION:Figure]] A typical protocol stack, from application to physical layer. + +See also: [Internet Protocol Suite](g-k.md#internet-protocol-suite), [L1](l-n.md#l1), [L2](l-n.md#l2). + +### Staff Days +A measure of effort: how much work an activity needs, in days of one person's time, as distinct from calendar days. + +See also: [Calendar Days](a-c.md#calendar-days). + +### Stage +Often a synonym for phase. More precisely, a phase can be divided into stages. + +See also: [Phase](o-r.md#phase). + +### Staged Delivery Lifecycle +A lifecycle that delivers a system in stages, with the most important functions first. + +See also: [Evolutionary Delivery Lifecycle](d-f.md#evolutionary-delivery-lifecycle), [Incremental Development](g-k.md#incremental-development). + +### Stakeholder +A person or organisation with an interest in a project's outcome, such as its customers, users and sponsors, and any group it affects. + +### Standard +An agreed, documented set of rules, conventions or requirements that work must follow. + +See also: [Construction Standard](a-c.md#construction-standard). + +### Statistical Estimation +Estimating with a statistical model built from historical data, usually predicting effort and time from size. It works best when calibrated on similar past projects. + +See also: [Parametric Estimation](o-r.md#parametric-estimation). + +### STB +**Set-Top Box.** A device that receives television signals, by aerial, satellite, cable or IP, and turns them into pictures and sound on a TV. + +See also: [IPTV](g-k.md#iptv), [DTT](d-f.md#dtt). + +### Story Mapping +Arranging user stories in two dimensions: along the user's journey from left to right, and by priority from top to bottom. The map helps plan releases. + +See also: [User Stories](#user-stories). + +### Story Splitting +Breaking a user story into smaller stories, each of which still has value of its own. + +See also: [User Stories](#user-stories), [Epic](d-f.md#epic). + +### Storyboard +A sequence of pictures showing a scenario or use case. + +See also: [Scenario](#scenario), [Low Fidelity Prototype](l-n.md#low-fidelity-prototype). + +### STRIDE Threat Model +Microsoft's mnemonic for six kinds of security threat: Spoofing, Tampering, Repudiation, Information disclosure, Denial of service and Elevation of privilege. Each one threatens a security property: authenticity, integrity, non-repudiation, confidentiality, availability and authorisation. + +See also: [Pen testing](o-r.md#pen-testing). + +### STP +**Spanning Tree Protocol.** The IEEE 802.1D protocol that stops loops in Ethernet networks by blocking redundant links so that one loop-free path remains, and unblocking them if the active path fails. Radia Perlman invented the algorithm. + +See also: [RSTP](o-r.md#rstp), [Switch](#switch). + +### Strategy +The overall approach taken to a problem or goal. + +### STUN +**Session Traversal Utilities for NAT.** A protocol (RFC 8489) with which a device behind a NAT discovers the public address and port the NAT has given it. ICE, SIP and WebRTC use it. + +See also: [ICE](g-k.md#ice), [NAT](l-n.md#nat). + +### Subversion +**SVN.** Apache Subversion, a centralised version control system designed as a successor to CVS. + +See also: [Git](g-k.md#git), [Version Control](#version-control). + +### Sustainable Pace +Working at a pace the team could keep up indefinitely, without overtime and burnout. + +See also: [XP](#xp). + +### SVC +**Switched Virtual Circuit.** A virtual circuit set up on demand for a call or transfer and cleared when it ends. + +See also: [PVC](o-r.md#pvc), [ATM](a-c.md#atm), [X.25](#x25). + +### Swift +Apple's compiled, multi-paradigm language for its platforms, released in 2014 as the successor to Objective-C. It is open source and also runs on Linux. + +See also: [Objective C](o-r.md#objective-c). + +### Switch +A network device that connects devices on a LAN and forwards each frame only to the port where its destination MAC address is. It learns those addresses from the traffic it sees. A layer-3 switch can also route. + +See also: [Hub](g-k.md#hub), [Router](o-r.md#router), [VLAN](#vlan). + +### System +A set of hardware, software and processes that work together. In a project, the system is what the project was set up to build. + +### System Test +A test of the whole system's behaviour, using a project build in the system test environment. + +See also: [Integration Test](g-k.md#integration-test), [System Test Environment](#system-test-environment). + +### System Test Environment +An environment that copies the live environment and its conditions as closely as possible, for system testing. + +See also: [System Test](#system-test). + +### SystemX +**System X.** The UK's national digital telephone exchange system, developed by the Post Office (later BT) with GEC, Plessey and STC, and introduced in the 1980s. It includes concentrators, digital local exchanges (DLEs) and trunk exchanges (DMSUs). + +See also: [DLE](d-f.md#dle), [PSTN](o-r.md#pstn). + +## T + +### T-Shirt Sizing +Estimating by sorting items into rough relative sizes, such as extra small, small, medium, large and extra large, rather than giving false precision. + +See also: [Relative Estimation](o-r.md#relative-estimation), [Points](o-r.md#points). + +### Task +A small, distinct unit of work in a project. + +See also: [Activity](a-c.md#activity), [Work Item](#work-item). + +### Task Board +A board with columns such as "To do", "In progress" and "Done", on which cards for tasks move as work progresses. + +See also: [Kanban Board](g-k.md#kanban-board), [Information Radiators](g-k.md#information-radiators). + +### Task Estimate +An estimate for a single task, usually made during planning and tracking and fed into work plans and detailed schedules. + +See also: [Project Estimate](o-r.md#project-estimate), [Estimate](d-f.md#estimate). + +### TCAP +**Transaction Capabilities Application Part.** The SS7 layer that manages dialogues between applications, such as MAP, INAP and CAP, using transaction IDs to run many at once. It encodes messages with ASN.1 BER. + +See also: [SS7](#ss7), [MAP](l-n.md#map), [INAP](g-k.md#inap), [CAP](a-c.md#cap). + +### Tcl/tk +Tcl is a dynamic scripting language, and Tk is the cross-platform GUI toolkit that grew up with it. Together they offer a quick way to build desktop interfaces, and other languages, such as Python's Tkinter, also use Tk. + +### TCP +**Transmission Control Protocol.** The internet's main transport protocol (RFC 9293). It gives applications a reliable, ordered, error-checked byte stream over IP, with flow and congestion control. The web, email and file transfer use it. + +See also: [UDP](#udp), [Internet Protocol Suite](g-k.md#internet-protocol-suite), [Out-of-order delivery](o-r.md#out-of-order-delivery). + +### Tcsh +An enhanced C shell that adds command-line editing and completion. It was long the default shell for the root user on FreeBSD. + +See also: [Csh](a-c.md#csh). + +### TDD +**Test-Driven Development.** Writing a failing unit test first, then the simplest code that passes it, then refactoring, in short repeated cycles. + +See also: [Unit Testing](#unit-testing), [Refactoring](o-r.md#refactoring), [BDD](a-c.md#bdd). + +### TDM +**Time-Division Multiplexing.** Sharing a channel by giving each signal its own repeating time slot. Digital telephony carries each call in a 64 kbit/s slot, for example 30 calls on an E1. + +See also: [Multiplex](l-n.md#multiplex), [PDH](o-r.md#pdh), [SDH](#sdh). + +### Team +In agile terms, a small group of people working on the same product or goal, nearly all of them full time. + +### Team Room +A space set aside for a team for the length of a project, so that its members, including the product owner, can work together closely. + +See also: [Information Radiators](g-k.md#information-radiators). + +### Technical Debt +The future cost of rework caused by choosing a quick solution now over a better one that would take longer. Like money, it gathers interest: left unpaid, it makes every later change harder. + +See also: [Refactoring](o-r.md#refactoring). + +### Template +An outline or framework for creating an artefact. + +### Test +A single test case, or testing in general. + +See also: [Testing](#testing), [Test Case](#test-case). + +### Test Activity +A specific test procedure, combining one or more test techniques and test types. + +### Test Case +**TC.** The inputs, steps and expected results that check whether a feature works or a requirement is met. + +See also: [Test Case Specification](#test-case-specification), [Test Plan](#test-plan). + +### Test Case Specification +**TCS.** A document listing the test cases that verify one or more features. + +See also: [Test Case](#test-case). + +### Test Design +Working out how to test a product: linking test cases to its requirements and design, when testing needs real analysis and structure. + +See also: [Test Design Specification](#test-design-specification). + +### Test Design Specification +**TDS.** A document recording the test design for a group of test cases. + +See also: [Test Design](#test-design). + +### Test Level +See [Test Type](#test-type). + +### Test Plan +**TP.** A document setting out the scope, approach, resources, test items and schedule of testing. + +See also: [Quality Plan](o-r.md#quality-plan), [Test Case](#test-case). + +### Test Technique +The method used in a test activity, such as boundary value analysis or equivalence partitioning. + +### Test Type +A category of testing, such as unit, integration, system or acceptance testing, defined by what it tests, how, why and when. + +### Testing +Running software to find defects and to show that it meets its requirements. + +See also: [Quality Control](o-r.md#quality-control), [Test Plan](#test-plan). + +### Three Amigos +A meeting of the three main perspectives on a piece of work, business, development and testing, to agree what it should do before, during and after development. + +See also: [ATDD](a-c.md#atdd), [BDD](a-c.md#bdd). + +### Three C's +**Card, Conversation, Confirmation.** The three parts of a user story: a short note on a card, the conversation that fills in the detail, and the acceptance tests that confirm it is done. + +See also: [User Stories](#user-stories). + +### Three Questions +The traditional structure of the daily stand-up: what did I complete, what will I do next, and what is in my way? + +See also: [Daily Scrum](d-f.md#daily-scrum). + +### TIA +**Telecommunications Industry Association.** The US trade body, accredited by ANSI, that develops standards such as TIA-568 for structured cabling. + +See also: [EIA](d-f.md#eia), [ANSI](a-c.md#ansi). + +### Timebox +A fixed, agreed period in which a person or team works towards a goal, and which ends on time whether or not everything is done. + +See also: [Sprints](#sprints), [Iteration](g-k.md#iteration). + +### TKIP +**Temporal Key Integrity Protocol.** The stop-gap Wi-Fi security protocol, from 802.11i, that replaced WEP on existing hardware. It is no longer secure and was deprecated in 2012. + +See also: [WEP](#wep), [WPA2](#wpa2). + +### TLS +**Transport Layer Security.** The protocol that encrypts and authenticates connections between applications, such as HTTPS. A handshake authenticates the server, usually with an X.509 certificate, and agrees keys. Symmetric encryption then protects the data. TLS 1.3 (RFC 8446) is current, and it replaced SSL. + +```mermaid +sequenceDiagram + participant C as Client + participant S as Server + C->>S: ClientHello (versions, ciphers, key share) + S->>C: ServerHello, certificate, Finished + C->>S: Finished + C-->>S: Encrypted application data +``` + +[[CAPTION:Figure]] A TLS 1.3 handshake, simplified. + +See also: [HTTPS](g-k.md#https), [DTLS](d-f.md#dtls), [X.509](#x509), [SSL](#ssl). + +### TLV +**Type-Length-Value.** An encoding in which each element has a type code, a length and then the value. Receivers can skip elements they do not understand, so formats can grow. BER, IS-IS and many other protocols use it. + +See also: [BER](a-c.md#ber). + +### TOGAF +**The Open Group Architecture Framework.** A widely used enterprise architecture framework. Its Architecture Development Method (ADM) guides architecture work across the business, data, application and technology domains. + +See also: [Architecture](a-c.md#architecture), [ADR](a-c.md#adr). + +### Token Ring +A LAN technology from IBM, standardised as IEEE 802.5. A token passes round a ring of stations, and only the station holding it may transmit. There are therefore no collisions. Ethernet replaced it. + +See also: [FDDI](d-f.md#fddi). + +### TOML +**Tom's Obvious, Minimal Language.** A configuration file format, created by Tom Preston-Werner, designed to be easy to read and to map clearly to a dictionary. Python's `pyproject.toml` and Rust's `Cargo.toml` use it. + +See also: [YAML](#yaml), [JSON](g-k.md#json). + +### Top Level Schedule +See [Business Schedule](a-c.md#business-schedule). + +### Top-Down Estimation +Estimating a whole system first, then dividing the total among its parts. + +See also: [Bottom-Up Estimation](a-c.md#bottom-up-estimation), [Macro Estimation](l-n.md#macro-estimation). + +### Triple DES +**3DES, or TDEA.** DES applied three times to each block with two or three keys, to extend its life after DES's 56-bit key became too short. It is slow and now deprecated in favour of AES. + +See also: [DES](d-f.md#des), [AES](a-c.md#aes). + +### TTY +**Teletypewriter.** Originally an electromechanical typewriter used as a terminal. On Unix the name now means any terminal device, including a terminal emulator window. + +See also: [Unix](#unix). + +### TrustZone +Arm's hardware security extension that splits a processor into a secure world and a normal world. The secure world holds keys, secure boot and trusted applications, isolated from the main operating system. It exists on Cortex-A and, as Armv8-M, on Cortex-M. + +See also: [Root of Trust](o-r.md#root-of-trust), [Secure Element](#secure-element). + +### TUP +**Telephone User Part.** The first SS7 call control protocol, for ordinary telephone calls without ISDN features. ISUP has largely replaced it. + +See also: [ISUP](g-k.md#isup), [SS7](#ss7). + +### Twisted pair +Cable in which the two wires of each circuit are twisted together, which cuts interference and crosstalk. It is used for telephone lines and Ethernet. + +See also: [Cat 5](a-c.md#cat-5), [Ethernet over twisted pair](d-f.md#ethernet-over-twisted-pair). + +## U + +### UA +**User Agent.** Software acting for a user. In HTTP, the browser or client, which names itself in the `User-Agent` header; in SIP, an endpoint that makes or receives calls. + +See also: [HTTP](g-k.md#http), [SIP](#sip). + +### Ubiquitous Language +In domain-driven design, a shared vocabulary drawn from the business domain, used consistently by everyone, from conversations and requirements through to the code. + +### UDP +**User Datagram Protocol.** A simple, connectionless transport protocol (RFC 768) that sends datagrams with port numbers and a checksum, but no guarantee of delivery or order. DNS, VoIP media and streaming use it, along with protocols that add their own reliability. + +[[CAPTION:Table]] The UDP header: four 16-bit fields, then the data. + +| Bits 0 to 15 | Bits 16 to 31 | +| --- | --- | +| Source port | Destination port | +| Length | Checksum | +| Data | Data | + +See also: [TCP](#tcp), [RTP](o-r.md#rtp), [DTLS](d-f.md#dtls). + +### UER +**Universal Edge Router.** Juniper's name for its broadband edge routers, which do the job of a BRAS. + +See also: [BRAS](a-c.md#bras), [BNG](a-c.md#bng). + +### UML + +**Unified Modeling Language.** + +The standard graphical language for modelling software systems, maintained by the Object Management Group. It was created by Grady Booch, Ivar Jacobson and James Rumbaugh in the mid-1990s. Its diagrams include class, sequence, activity, state and use case diagrams. + +See also: [Class Model](a-c.md#class-model), [Sequence Model](#sequence-model), [Use Case](#use-case). + +### UMTS +**Universal Mobile Telecommunications System.** The 3GPP third-generation (3G) mobile system, which evolved from GSM. It uses wideband CDMA radio, and HSPA later speeded up its data. + +See also: [W-CDMA](#w-cdma), [UTRAN](#utran), [GSM](g-k.md#gsm), [LTE (4G)](l-n.md#lte-4g). + +### UNI +**User-Network Interface.** The demarcation between a service provider's network and a customer's equipment, where the provider's responsibility ends. + +See also: [NNI](l-n.md#nni), [EVC](d-f.md#evc). + +### Unicast +Sending data from one sender to one receiver, each identified by its own address. Most internet traffic is unicast. + +See also: [Multicast](l-n.md#multicast), [Broadcast](a-c.md#broadcast), [Anycast](a-c.md#anycast). + +### Unicode +The standard that gives a unique number, or code point, to every character in the world's writing systems, plus symbols and emoji. It is kept in step with ISO/IEC 10646. UTF-8 and UTF-16 are ways of encoding it. + +See also: [UTF-8](#utf-8), [UTF-16](#utf-16), [ASCII](a-c.md#ascii). + +### Unified Communications +**UC.** Bringing an organisation's communication services, such as voice, video, messaging, presence, conferencing and voicemail, together behind one consistent user experience across devices. + +See also: [VoIP](#voip), [SIP](#sip). + +### Unit Test +The lowest level of component test: a test of one small piece of code on its own. + +See also: [Unit Testing](#unit-testing). + +### Unit Testing +Writing and running small automated tests, written by the developers, that each check a narrow piece of the code. + +See also: [Unit Test](#unit-test), [TDD](#tdd), [Mock Objects](l-n.md#mock-objects). + +### Unix +A family of multi-user, multitasking operating systems descended from the original developed at Bell Labs by Ken Thompson, Dennis Ritchie and others from 1969. BSD, Solaris, AIX and macOS are Unix systems; Linux is Unix-like. + +See also: [Linux](l-n.md#linux), [POSIX](o-r.md#posix), [Sh](#sh). + +### Update +Planned work to bring an artefact up to date with the project's current needs. + +See also: [Rework](o-r.md#rework). + +### Upstream +In a project, the early activities and artefacts, such as chartering, planning, requirements and architecture. In networking, the direction from the customer towards the network. + +See also: [Downstream](d-f.md#downstream). + +### URI +**Uniform Resource Identifier.** A string that identifies a resource (RFC 3986). URLs, which say where to find it, and URNs, which name it, are both kinds of URI. + +See also: [URL](#url), [URN](#urn). + +### URL +**Uniform Resource Locator.** A URI that says how and where to get a resource: a scheme, such as `https`, a host, a path and optional query and fragment, as in `https://example.com/page?id=1#top`. + +See also: [URI](#uri), [URN](#urn), [HTTP](g-k.md#http). + +### URN +**Uniform Resource Name.** A URI that names a resource permanently, without saying where it is, as in `urn:isbn:0451450523`. + +See also: [URI](#uri), [URL](#url). + +### Usability Testing +Watching real users try to do realistic tasks with a product, to find where it is hard to use. + +See also: [User Experience](#user-experience). + +### Use Case +A description of how a user (actor) interacts with a system to achieve a goal, including the main path and alternatives. + +See also: [Use Case Model](#use-case-model), [Use Case Specification](#use-case-specification), [Nominal Path](l-n.md#nominal-path). + +### Use Case Model +The set of use cases and actors that describes a system's behaviour from the outside. + +See also: [Use Case](#use-case), [UML](#uml). + +### Use Case Specification +The document that describes one use case in full. + +See also: [Use Case](#use-case). + +### User Experience +**UX.** The whole of a person's experience of using a product, including but going beyond its user interface: how useful, easy and pleasant it is. + +See also: [User Interface](#user-interface), [Usability Testing](#usability-testing), [Personas](o-r.md#personas). + +### User Interface +**UI.** The part of a system through which people interact with it, such as screens, controls and messages. + +See also: [User Interface Design](#user-interface-design), [User Experience](#user-experience). + +### User Interface Design +Designing how people interact with a system: layout, controls, flows and feedback. + +See also: [User Interface](#user-interface), [User Interface Prototype](#user-interface-prototype). + +### User Interface Prototype +A prototype built to explore a user interface's behaviour or look and feel. + +See also: [High Fidelity Prototype](g-k.md#high-fidelity-prototype), [Low Fidelity Prototype](l-n.md#low-fidelity-prototype). + +### User Plane +The part of a network that carries users' traffic, as opposed to the control plane, which carries signalling. In routers it is also called the data plane or forwarding plane. In mobile networks, separating the two planes lets each scale on its own. + +See also: [Data Plane](d-f.md#data-plane), [Control Plane](a-c.md#control-plane), [Management Plane](l-n.md#management-plane). + +### User Stories +Short descriptions of functionality from the user's point of view, agreed with the customer or product owner, that the team uses to divide up the work. + +See also: [Role-feature-reason](o-r.md#role-feature-reason), [INVEST](g-k.md#invest), [Three C's](#three-cs), [Epic](d-f.md#epic). + +### UTC +**Coordinated Universal Time.** The world's primary time standard, kept by atomic clocks and adjusted with leap seconds to stay close to the Earth's rotation. It has no daylight saving time, and for everyday purposes it is the same as GMT. + +See also: [NTP](l-n.md#ntp). + +### UTF-16 +A Unicode encoding that uses one 16-bit unit for characters in the Basic Multilingual Plane and two units, a surrogate pair, for the rest. Windows, Java and JavaScript use it internally. UTF-32, by contrast, uses a fixed 32 bits for every code point. + +See also: [Unicode](#unicode), [UTF-8](#utf-8). + +### UTF-8 +The most widely used Unicode encoding, designed by Ken Thompson and Rob Pike. It uses one to four bytes per character, and the first 128 characters are the same as ASCII, so ASCII text is valid UTF-8. It is the default encoding of the web. + +See also: [Unicode](#unicode), [UTF-16](#utf-16), [ASCII](a-c.md#ascii). + +### UTRAN +**UMTS Terrestrial Radio Access Network.** The 3G radio access network: the Node Bs and the RNCs that control them. + +See also: [Node B](l-n.md#node-b), [RNC](o-r.md#rnc), [UMTS](#umts), [E-UTRAN](d-f.md#e-utran). + +## V + +### V Model +A development model that extends waterfall by pairing each specification and design stage with the test stage that checks it. Requirements pair with acceptance testing, and so on down to unit tests. Drawn out, the stages form a V. + +```mermaid +flowchart LR + R[Requirements] --> SD[System design] --> AD[Architecture] --> MD[Module design] --> C[Coding] + C --> UT[Unit testing] --> IT[Integration testing] --> ST[System testing] --> AT[Acceptance testing] + R -. verified by .- AT + SD -. verified by .- ST + AD -. verified by .- IT + MD -. verified by .- UT +``` + +[[CAPTION:Figure]] The V model: each design stage is verified by a matching test stage. + +See also: [Waterfall](#waterfall), [Testing](#testing). + +### V.90 {#v90} +The ITU-T standard, from 1998, for 56 kbit/s dial-up modems. It achieves 56 kbit/s downstream and 33.6 kbit/s upstream by using the digital connection at the network end. + +See also: [V.92](#v92). + +### V.92 {#v92} +The ITU-T successor to V.90, which raised upstream speed to 48 kbit/s and added quicker connection and modem-on-hold. + +See also: [V.90](#v90). + +### VAD +**Voice Activity Detection.** Detecting whether speech is present in an audio signal. VoIP and mobile systems use it to stop sending during silence, which saves bandwidth, and generate comfort noise at the other end. + +See also: [CNG](a-c.md#cng), [VoIP](#voip). + +### VB +**Visual Basic.** Microsoft's event-driven language and IDE, first released in 1991, for building Windows applications quickly from forms and components. Classic VB became legacy in 2008; VB.NET is its .NET successor. + +See also: [BASIC](a-c.md#basic), [VBS](#vbs), [RAD](o-r.md#rad). + +### VBS +**VBScript.** Microsoft's scripting language based on Visual Basic, used for Windows administration and old web pages. Microsoft is removing it from Windows. + +See also: [VB](#vb). + +### VC +**Virtual Circuit.** A connection across a packet network that behaves like a dedicated circuit between two endpoints, set up before data flows. X.25, Frame Relay and ATM use virtual circuits. + +See also: [PVC](o-r.md#pvc), [SVC](#svc), [VCI](#vci). + +### VCI +**Virtual Channel Identifier.** The 16-bit field in an ATM cell header that, with the VPI, identifies the virtual channel the cell belongs to. + +See also: [VPI](#vpi), [ATM](a-c.md#atm). + +### VCID +**Virtual Circuit Identifier.** The identifier that both ends of a pseudowire use to match up the same circuit, for example in an MPLS VPWS. + +See also: [PW](o-r.md#pw), [VPWS](#vpws). + +### VDSL +**Very-high-bit-rate DSL.** DSL using frequencies up to 30 MHz on short lines. VDSL2 (G.993.2) gives tens of megabits per second, and up to around 80 Mbit/s downstream from a street cabinet. It is the technology of fibre-to-the-cabinet broadband. + +See also: [ADSL](a-c.md#adsl), [G.Fast](g-k.md#gfast), [PCP](o-r.md#pcp). + +### Velocity +The amount of work, usually in story points, that a team completes in an iteration. Teams use it to forecast what they can take on next. + +See also: [Points](o-r.md#points), [Burndown Chart](a-c.md#burndown-chart). + +### Verifier +In an inspection, the person who checks that the rework has been done properly. + +See also: [Inspection](g-k.md#inspection). + +### Version +A formally released revision of an artefact, recognised by configuration management. + +See also: [Revision](o-r.md#revision), [Semantic Versioning](#semantic-versioning). + +### Version Control +Recording every change to files, such as source code, so that any earlier version can be recovered and several people can work in parallel and merge their work. Git is the most widely used tool. + +See also: [Git](g-k.md#git), [Subversion](#subversion), [SCM](#scm). + +### VHDL +**VHSIC Hardware Description Language.** A language, standardised as IEEE 1076, for describing and simulating digital hardware, from systems down to logic gates. It came out of the US Very High-Speed Integrated Circuits programme in the 1980s. Verilog is its main alternative. + +### VISP +**Virtual ISP.** An internet service provider that sells another ISP's service under its own brand. + +See also: [ISP](g-k.md#isp), [MVNO](l-n.md#mvno). + +### VLAN +**Virtual LAN.** A separate broadcast domain created on shared switches, usually by tagging frames with an 802.1Q VLAN ID, so that one physical network carries several isolated LANs. + +See also: [Dot1Q](d-f.md#dot1q), [Dot1Q trunking](d-f.md#dot1q-trunking), [Switch](#switch). + +### VLR +**Visitor Location Register.** The database, usually built into each MSC, of the subscribers currently in its area. It copies their details from their HLR. + +See also: [HLR](g-k.md#hlr), [MSC](l-n.md#msc). + +### VM +**Virtual Machine.** A software emulation of a computer, on which an operating system and applications run as if on real hardware. A hypervisor shares the physical machine between several VMs. + +See also: [Docker](d-f.md#docker), [IaaS](g-k.md#iaas). + +### VOD +**Video on Demand.** Letting viewers choose and watch video when they want, rather than at a broadcast time, by streaming or downloading. + +See also: [IPTV](g-k.md#iptv), [STB](#stb). + +### VoIP +**Voice over IP.** Carrying voice calls over IP networks, with signalling protocols such as SIP to set up calls and RTP to carry the media. + +See also: [SIP](#sip), [RTP](o-r.md#rtp), [SBC](#sbc), [VoLTE](#volte). + +### VoLTE +**Voice over LTE.** Voice calls over an LTE network as IP packets, using IMS, following the GSMA IR.92 profile. It needs no circuit-switched network, connects calls faster and supports HD voice. + +See also: [IMS](g-k.md#ims), [LTE (4G)](l-n.md#lte-4g), [AMR-WB](a-c.md#amr-wb). + +### Vorbis +An open, royalty-free lossy audio codec from the Xiph.Org Foundation, usually used in the Ogg container (Ogg Vorbis). Opus has largely replaced it. + +See also: [OPUS](o-r.md#opus), [MP3](l-n.md#mp3). + +### VPI +**Virtual Path Identifier.** The field in an ATM cell header that identifies a virtual path, a bundle of virtual channels. See [VCI](#vci). + +### VPLS +**Virtual Private LAN Service.** A provider service that joins several customer sites into one Ethernet broadcast domain over an MPLS network, using a mesh of pseudowires. It is defined in RFCs 4761 and 4762. + +See also: [L2VPN](l-n.md#l2vpn), [PW](o-r.md#pw), [VPWS](#vpws). + +### VPN +**Virtual Private Network.** A private network built over a shared or public one, such as the internet or a provider's MPLS core. It uses tunnelling and often encryption, so that remote sites or users act as if directly connected. + +See also: [IPSec](g-k.md#ipsec), [L3VPN](l-n.md#l3vpn), [L2VPN](l-n.md#l2vpn). + +### VPWS +**Virtual Private Wire Service.** A point-to-point layer-2 service, such as Ethernet, carried over an MPLS network by a pseudowire. It is also called a virtual leased line or Ethernet over MPLS (EoMPLS). + +See also: [PW](o-r.md#pw), [VPLS](#vpls), [EPWS](d-f.md#epws). + +### VRF +**Virtual Routing and Forwarding.** Several separate routing tables in one router, so that different customers or networks, even with overlapping addresses, stay apart. It is the building block of MPLS layer-3 VPNs. + +See also: [L3VPN](l-n.md#l3vpn), [CE](a-c.md#ce). + +## W + +### W-CDMA +**Wideband CDMA.** The UMTS air interface, which uses direct-sequence CDMA over pairs of 5 MHz channels. + +See also: [UMTS](#umts), [CDMA](a-c.md#cdma). + +### W3C +**World Wide Web Consortium.** The international body, founded by Tim Berners-Lee, that develops standards for the web, such as HTML, CSS and XML. + +See also: [XML](#xml), [CSS](a-c.md#css). + +### Walkthrough +An informal review in which the author takes one or more people through an artefact to find defects. + +See also: [Review](o-r.md#review), [Desk Check](d-f.md#desk-check). + +### WAN +**Wide Area Network.** A network that spans a large area, linking sites in different cities or countries, usually over carriers' circuits. The internet is the largest WAN. + +See also: [LAN](l-n.md#lan), [MAN](l-n.md#man). + +### WANET +**Wireless Ad hoc Network.** A decentralised wireless network with no routers or access points, in which every node forwards traffic for the others. A MANET is the mobile kind. + +See also: [MANET](l-n.md#manet), [Wireless Mesh Network](#wireless-mesh-network). + +### WAP +**Wireless Access Point.** A device that lets Wi-Fi devices connect to a wired network. WAP also stood for Wireless Application Protocol, an early way of browsing on mobile phones. + +See also: [Wi-Fi](#wi-fi), [Wireless Repeater](#wireless-repeater). + +### Waterfall +A sequential development model in which work flows through requirements, design, construction, testing and deployment, each finished before the next starts. Winston Royce's 1970 paper, often cited as its origin, described it as risky. + +See also: [Waterfall Lifecycle](#waterfall-lifecycle), [V Model](#v-model), [Spiral Model](#spiral-model). + +### Waterfall Lifecycle +A lifecycle that moves through ordered phases, from concept to delivery, with a review at the end of each. + +See also: [Waterfall](#waterfall). + +### WBC +**Wholesale Broadband Connect.** BT Wholesale's broadband access product on the 21CN network. ISPs connect at regional aggregation points to collect their customers' traffic. + +See also: [WBMC](#wbmc), [BT 21CN](a-c.md#bt-21cn). + +### WBCC +**Wholesale Broadband Connect Converge.** A BT Wholesale package, based on WBC, that combined voice and broadband on one bill for the ISP. + +See also: [WBC](#wbc). + +### WBMC +**Wholesale Broadband Managed Connect.** A BT Wholesale product, built on WBC, in which BT carries the traffic end to end to a single handover point. It replaced IPStream. + +See also: [WBC](#wbc), [IPSC](g-k.md#ipsc). + +### Weekly Individual Plan +A plan in which each person sets their miniature milestones for the week. + +See also: [Miniature Milestone](l-n.md#miniature-milestone). + +### WEP +**Wired Equivalent Privacy.** The original Wi-Fi security from 1997, which is easily broken. WPA and WPA2 replaced it, and it was deprecated in 2004. + +See also: [WPA2](#wpa2), [TKIP](#tkip). + +### What Requirement +See [Functional Requirement](d-f.md#functional-requirement). + +### Why Requirement +See [Business Requirement](a-c.md#business-requirement). + +### Wi-Fi +Wireless LAN technology based on the IEEE 802.11 standards. Wi-Fi is the Wi-Fi Alliance's trademark for certified products. Recent generations are numbered, such as Wi-Fi 6 (802.11ax) and Wi-Fi 7 (802.11be). + +See also: [802.11](#80211), [WAP](#wap), [WPA2](#wpa2), [SSID](#ssid). + +### Wiki +A website that its users edit together in the browser, usually with simple markup. + +See also: [Document Collaboration](d-f.md#document-collaboration), [Knowledge Management](g-k.md#knowledge-management). + +### WiMAX +**Worldwide Interoperability for Microwave Access.** Wireless broadband based on the IEEE 802.16 standards, promoted as an alternative to DSL and as a 4G candidate. LTE won out. + +See also: [LTE (4G)](l-n.md#lte-4g). + +### WIN-T +**Warfighter Information Network-Tactical.** The US Army's mobile tactical communications network, giving units secure voice, data and video on the move without fixed infrastructure. + +See also: [MANET](l-n.md#manet). + +### Wireless Mesh Network +A wireless network in which nodes connect in a mesh and relay traffic for each other, with some nodes acting as gateways to a wired network. The nodes rarely move, so routes stay stable. + +See also: [WANET](#wanet), [MANET](l-n.md#manet), [Network Topologies](l-n.md#network-topologies). + +### Wireless Repeater +A device that receives a Wi-Fi signal and rebroadcasts it to extend coverage. Also called a range extender. + +See also: [WAP](#wap). + +### Wireshark +A free, open-source packet analyser, formerly called Ethereal, used for troubleshooting networks and developing protocols. + +See also: [Packet sniffing](o-r.md#packet-sniffing). + +### WISP +**Wireless ISP.** An internet service provider whose access network is wireless, such as fixed wireless or Wi-Fi. + +See also: [ISP](g-k.md#isp). + +### WLR +**Wholesale Line Rental.** A UK product that let a provider rent a phone line from Openreach and bill the customer for line and calls. It is being withdrawn as the copper phone network closes. + +See also: [CPS](a-c.md#cps), [SMPF](#smpf), [SoGEA](#sogea). + +### WMA +**Windows Media Audio.** Microsoft's family of audio codecs, including lossy, professional, lossless and voice versions. + +See also: [MP3](l-n.md#mp3), [AAC](a-c.md#aac). + +### Work Breakdown Structure +**WBS.** A hierarchical breakdown of all a project's work into work packages. Larger projects keep it as a separate document; smaller ones hold it in the work plan or schedule. + +See also: [Work Package](#work-package), [Work Plan](#work-plan). + +### Work Item +A unit of tracked work, such as a task, story or defect. Also used for the artefact the work produces. + +See also: [Artefact](a-c.md#artefact), [Item](g-k.md#item). + +### Work Package +The lowest level of a work breakdown structure, often a tangible deliverable, which is broken down further into activities and tasks for estimating and scheduling. + +See also: [Work Breakdown Structure](#work-breakdown-structure). + +### Work Plan +A plan of the work packages and their task estimates, used to plan, track and control detailed work. + +See also: [Work Package](#work-package), [Detailed Schedule](d-f.md#detailed-schedule), [Earned Value](d-f.md#earned-value). + +### Work Product +See [Artefact](a-c.md#artefact). + +### WPA2 +**Wi-Fi Protected Access 2.** The Wi-Fi security certification, from 2004, based on the full IEEE 802.11i standard with AES encryption. It replaced WEP and WPA, and WPA3 now succeeds it. + +See also: [WEP](#wep), [TKIP](#tkip), [EAP](d-f.md#eap). + +### WPS +**Wi-Fi Protected Setup.** A Wi-Fi Alliance scheme, from 2006, for adding devices to a network with a button or PIN rather than a passphrase. The PIN method is insecure and should be disabled. + +See also: [WPA2](#wpa2). + +### Write-only code +Code so hard to read that nobody, often not even its author, can understand it later. + +See also: [Construction Standard](a-c.md#construction-standard). + +### WS-BPEL +**Web Services Business Process Execution Language.** The full name of [BPEL](a-c.md#bpel). + +### WSDL +**Web Services Description Language.** An XML language for describing a web service's interface: its operations, messages, data types and endpoints. It is mostly used with SOAP. + +See also: [SOAP](#soap), [XML Schema](#xml-schema). + +## X + +### X.25 {#x25} +An ITU-T packet-switching protocol suite for WANs, from 1976, using virtual circuits with error correction at every hop. It was widely used in the 1980s, for example for cash machines, and IP has replaced it. + +See also: [Frame Relay](d-f.md#frame-relay), [HDLC](g-k.md#hdlc). + +### X.509 {#x509} +The ITU-T standard format for public key certificates, which bind an identity, such as a host name, to a public key under a CA's signature. TLS and many other protocols use them. + +See also: [CA](a-c.md#ca), [TLS](#tls), [DER](d-f.md#der). + +### XML +**Extensible Markup Language.** A W3C text format for structured documents and data, with user-defined, nested elements. It is the basis of many formats and protocols, such as SOAP and SVG. + +See also: [XML Schema](#xml-schema), [JSON](g-k.md#json), [SGML](#sgml). + +### XML Schema +A description of the allowed structure and content of a type of XML document, used to validate documents. DTD, XSD and RELAX NG are schema languages. + +See also: [Xsd](#xsd), [XML](#xml). + +### XML-RPC +A simple remote procedure call protocol that encodes calls in XML and sends them over HTTP. SOAP grew out of it. + +See also: [JSON-RPC](g-k.md#json-rpc), [SOAP](#soap), [RPC](o-r.md#rpc). + +### XMPP +**Extensible Messaging and Presence Protocol.** An open, XML-based protocol for instant messaging and presence, originally called Jabber. It has been extended for many other real-time uses. + +See also: [SIMPLE](#simple). + +### XP +**Extreme Programming.** An agile method that focuses on engineering practices, such as pair programming, test-driven development, continuous integration, refactoring and small releases. + +See also: [Pair Programming](o-r.md#pair-programming), [TDD](#tdd), [Agile development](a-c.md#agile-development). + +### Xsd +**XML Schema Definition.** The W3C's XML schema language. It describes the elements and attributes an XML document may contain, with data types, so documents can be validated. + +See also: [XML Schema](#xml-schema). + +### XSS +**Cross-Site Scripting.** A web vulnerability in which an attacker gets a site to include their script in pages other users view. The script then runs with the site's privileges in the victims' browsers. Encoding output and a content security policy prevent it. + +See also: [Pen testing](o-r.md#pen-testing). + +## Y + +### YAML +**YAML Ain't Markup Language.** A human-readable data format that uses indentation for nesting, widely used for configuration files. YAML 1.2 is a superset of JSON. + +See also: [JSON](g-k.md#json), [TOML](#toml). + +## Z + +### ZigBee +A low-power, low-rate wireless mesh protocol based on IEEE 802.15.4, used in home automation and sensors. It is simpler and uses less power than Bluetooth or Wi-Fi. + +See also: [Bluetooth](a-c.md#bluetooth), [Wireless Mesh Network](#wireless-mesh-network). + +## Numbers + +### .NET +Microsoft's software platform for building and running applications. Code compiles to an intermediate language that the Common Language Runtime runs, with a large class library. The original .NET Framework was Windows only; modern .NET is open source and cross-platform. + +See also: [C#](a-c.md#c_2), [VB](#vb). + +### 100 Mbps (Fast Ethernet) {#100-mbps-fast-ethernet} +**Fast Ethernet.** Ethernet at 100 Mbit/s, introduced in 1995 as IEEE 802.3u. 100BASE-TX over Cat 5 cable is by far the most common form. + +See also: [Gigabit Ethernet](g-k.md#gigabit-ethernet), [Ethernet over twisted pair](d-f.md#ethernet-over-twisted-pair). + +### 5ESS {#5ess} +A digital telephone switch developed by Western Electric for AT&T, first in service in 1982. It became one of the most widely used local exchanges in the United States. + +See also: [SystemX](#systemx), [Class 5 Softswitch](a-c.md#class-5-softswitch). + +### 5G {#5g} +The fifth generation of mobile networks, standardised by 3GPP from Release 15 (2018) to meet the ITU's IMT-2020 targets. It uses the New Radio (NR) air interface and a service-based core. It offers faster broadband, low-latency services and very large numbers of IoT devices. Speeds depend heavily on the frequency band used. + +See also: [LTE (4G)](l-n.md#lte-4g), [OFDMA](o-r.md#ofdma), [MIMO](l-n.md#mimo). + +### 802.11 {#80211} +The IEEE family of standards for wireless LANs, first published in 1997, which defines the physical and MAC layers that Wi-Fi products use. Amendments add speed and features, such as 802.11n, ac, ax and be. + +See also: [Wi-Fi](#wi-fi), [IEEE](g-k.md#ieee). + +### 802.3 Physical Layer {#8023-physical-layer} +**IEEE 802.3.** The IEEE working group and family of standards that define wired Ethernet: the physical layers and the MAC. They cover speeds from 10 Mbit/s to hundreds of gigabits per second, over copper and fibre. + +See also: [Ethernet over twisted pair](d-f.md#ethernet-over-twisted-pair), [MAC](l-n.md#mac), [CSMA](a-c.md#csma). diff --git a/py-doc.yml b/py-doc.yml index 6b6f4cf..056fbd1 100644 --- a/py-doc.yml +++ b/py-doc.yml @@ -50,9 +50,16 @@ documents: outputs: {docx: {}, pdf: {}} glossary: - # Glossary. The section's own pull request lists the rest of its files here. + # Glossary: the index, then one file per letter group. Each term is a ### heading, so it has + # its own anchor (content/glossary/redirects.tsv maps the old one-page-per-term URLs to them). sources: - content/glossary/index.md + - content/glossary/a-c.md + - content/glossary/d-f.md + - content/glossary/g-k.md + - content/glossary/l-n.md + - content/glossary/o-r.md + - content/glossary/s-z.md outputs: {docx: {}, pdf: {}} templates: