Glossary

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ACM Code of Ethics(also: ACM Code of Ethics and Professional Conduct)

A statement of professional ethics maintained by the Association for Computing Machinery (ACM) that sets out the moral and professional responsibilities of computing practitioners. Significantly revised in 2018, the Code explicitly addresses accessibility and inclusion, stating…

ACT Rules(also: Accessibility Conformance Testing Rules, ACT-R)

A set of standardized, machine-readable test rules developed by the W3C that provide specific, objective criteria for evaluating whether web content meets accessibility requirements like WCAG success criteria. ACT Rules aim to reduce inconsistency between different automated…

AD Guidelines(also: Audio Description Guidelines, AD Standards)

Established rules and best practices that govern the creation of audio descriptions for video and live performances. AD guidelines cover aspects such as what to describe (actions, characters, settings, on-screen text), language style (present tense, third person, objective),…

ADA(also: Americans with Disabilities Act)

A landmark United States civil rights law enacted in 1990 that prohibits discrimination against individuals with disabilities in all areas of public life, including employment, education, transportation, and access to public and private places open to the general public. The ADA…

ADA Compliance(also: Americans with Disabilities Act Compliance)

Adherence to the requirements of the Americans with Disabilities Act (ADA), a 1990 US civil rights law that prohibits discrimination against people with disabilities in public accommodations, employment, transportation, telecommunications, and government services. ADA compliance…

ARIA(also: Accessible Rich Internet Applications, WAI-ARIA)

A W3C specification that provides a framework of roles, states, and properties to make dynamic web content and custom user interface controls accessible to assistive technologies. ARIA supplements HTML semantics where native elements are insufficient. The first rule of ARIA is:…

ASCII(also: American Standard Code for Information Interchange)

A character encoding standard that uses numeric codes to represent letters, digits, punctuation, and control characters in computers and communication equipment. ASCII assigns values 0-127 to 128 characters, covering the basic Latin alphabet. In accessibility contexts, ASCII is…

ATAG(also: Authoring Tool Accessibility Guidelines)

A W3C standard that provides guidelines for making authoring tools—such as content management systems, HTML editors, and website builders—both accessible to authors with disabilities and capable of producing accessible content. ATAG 2.0, published in 2015, is organized into two…

Access For All(also: ISO/IEC 24751, IMS Access For All, AfA)

An international standard (ISO/IEC 24751) for describing user accessibility needs and preferences in a portable, application-independent format. Originally developed by the IMS Global Learning Consortium for educational contexts, it was adopted as an ISO standard and uses XML…

Accessibility API Mapping(also: AAM, Accessibility API Mappings, Acc API Mapping)

Accessibility API Mappings (AAMs) are W3C specifications that define how the semantics of web content technologies — such as HTML, SVG, and WAI-ARIA — correspond to features in platform accessibility APIs like MSAA/UIA on Windows, ATK/AT-SPI on Linux, and NSAccessibility on…

Accessibility Conformance Testing(also: ACT, ACT Rules Format)

A W3C technical recommendation that defines a standardized format for writing rules to test web accessibility. The ACT Rules Format provides a consistent structure for describing what to test and what outcomes to expect, aiming to reduce inconsistency between different automated…

Accessibility Evaluation Framework(also: A11y Assessment Framework, Accessibility Testing Framework)

A structured methodology for systematically assessing the accessibility of digital content, products, or services against established standards and guidelines. Effective frameworks define the criteria to be evaluated, the methods for evaluation (automated testing, manual…

Accessibility conformance(also: WCAG conformance, Accessibility compliance)

The degree to which a digital product meets the requirements of an accessibility standard such as WCAG, typically assessed at Level A, AA, or AAA. While conformance provides a measurable baseline for accessibility, it does not guarantee usability for all disabled users — a site…

Accessibility conformance report(also: ACR, VPAT, Voluntary Product Accessibility Template)

A document that records the degree to which a product or service meets accessibility standards such as WCAG, Section 508, or EN 301 549. In enterprise settings, conformance reports are a primary deliverable of the accessibility testing process, used to communicate compliance…

Accessibility ontology(also: A11y ontology, Accessibility knowledge graph)

A formal, structured representation of accessibility concepts, their properties, and the relationships between them, typically expressed in OWL (Web Ontology Language). Accessibility ontologies model domains such as disabilities, assistive technologies, standards, testing…

Accessible Authentication(also: WCAG 3.3.7, Accessible Authentication (Minimum))

A web accessibility requirement introduced in WCAG 2.2 (Success Criterion 3.3.7) that mandates for each step in an authentication process relying on a cognitive function test — such as remembering a password, solving a puzzle, or transcribing distorted text — at least one…

Accessible Canada Act(also: ACA, Canadian Accessibility Act)

Canadian federal legislation (S.C. 2019, c. 10) that aims to make Canada barrier-free by 2040 by requiring federally regulated organisations (banks, telecommunications, transportation, the federal government) to identify, remove, and prevent barriers in areas including…

Accessible PDF(also: Tagged PDF, PDF/UA)

An accessible PDF is a Portable Document Format file that has been structured with tags, reading order, alternative text for images, and other metadata so that it can be navigated and read by assistive technologies such as screen readers. The PDF/UA (Universal Accessibility)…

Adaptive Multi-Rate Codec(also: AMR, AMR Codec, AMR-NB)

A family of audio codecs used in mobile telephony to encode voice for transmission. AMR-NB (narrowband) operates at 300-3,400 Hz with bit rates from 4.75-12.2 kbps, while AMR-WB (wideband, also called HD Voice) extends to 50-7,000 Hz at 6.6-23.85 kbps. AMR-WB is adopted by 3GPP…

Americans with Disabilities Act(also: ADA, ADA 1990)

The Americans with Disabilities Act (ADA) is landmark US civil rights legislation enacted in 1990 that prohibits discrimination against individuals with disabilities in all areas of public life, including employment, education, transportation, and public accommodations. Title II…

Application Profile(also: Metadata Application Profile)

A customization of an existing metadata standard that selects, constrains, or extends elements to meet the requirements of a particular community or application. In accessibility, application profiles are used to add accessibility-specific properties to general-purpose metadata…

Audio description(also: AD, Described video, Video description)

Narration added to a media soundtrack that describes important visual information — such as actions, characters, scene changes, and on-screen text — that cannot be understood from the main audio alone. Audio description makes video and live performance content accessible to…

Authoring Tool Accessibility Guidelines (ATAG)(also: ATAG, ATAG 2.0)

A W3C Web Accessibility Initiative standard that provides guidelines for designing authoring tools — such as content management systems, website builders, and code editors — that are both accessible to authors with disabilities and capable of producing accessible web content.…

Automated accessibility testing(also: Automated a11y testing, Accessibility checker)

The use of software tools to automatically evaluate digital content against accessibility standards, checking for issues like missing alt text, colour contrast violations, missing form labels, untagged PDF structure, and incorrect heading hierarchy. Automated testing can…

BBC Mobile Accessibility Guidelines(also: BBC MAG)

A comprehensive set of accessibility standards developed by the BBC for mobile application and web content design. The guidelines cover areas including design, editorial, code, and testing, with specific recommendations for touch targets, text sizing, color contrast, and…

BITV(also: Barrierefreie Informationstechnik-Verordnung, Barrier-Free Information Technology Regulation)

BITV (Barrierefreie Informationstechnik-Verordnung) is the German federal regulation on accessible information technology, mandating that federal government websites and applications be accessible to people with disabilities. First introduced in 2002 and updated as BITV 2.0 in…

BS 8878(also: British Standard 8878, Web Accessibility Code of Practice)

A British Standard published in 2010 that provides a code of practice for web accessibility. BS 8878 defines a 16-step process for implementing web accessibility within organisations, taking a user-centred approach that goes beyond technical conformance with WCAG. It emphasises…

Bharati Braille(also: Indian Braille)

A unified Braille standard for writing text in Indian languages using the six-dot Braille format. Bharati Braille assigns the same Braille cell to phonetically equivalent characters across different Indian languages (Hindi, Bengali, Tamil, etc.), meaning that a reader familiar…

Braille Authority of North America(also: BANA)

The standards-setting body responsible for establishing braille codes and guidelines for the production of braille materials in the United States and Canada. BANA publishes guidelines for tactile graphics, braille formatting, and specialized braille codes for mathematics, music,…

CIE L*a*b*(also: CIELAB, Lab Color Space, CIE Lab)

A perceptually uniform colour space defined by the International Commission on Illumination (CIE) in 1976, where the numerical distance between two colour values approximates the perceived visual difference between those colours. The three dimensions are L* (lightness, from…

CIE LUV(also: CIELUV, CIE 1976 L*u*v*)

A perceptually uniform color space defined by the International Commission on Illumination (CIE) that separates color into luminance (L*) and two chromaticity coordinates (u* and v*). Unlike RGB, which is tied to display hardware and not perceptually uniform, equal distances in…

Captioning Key(also: DCMP Captioning Key)

A set of guidelines and best practices for creating high-quality captions, most notably published by the Described and Captioned Media Program (DCMP). The Captioning Key covers standards for caption accuracy, consistency, placement, and the representation of non-speech sounds.…

Checkpoint(also: WCAG Checkpoint, Success Criterion, Accessibility Checkpoint)

A checkpoint is a specific, testable accessibility requirement in a set of guidelines — for example, 'provide a text equivalent for every non-text element' is WCAG 1.0 checkpoint 1.1. The term is strongly associated with WCAG 1.0, which was organised into 65 numbered checkpoints…

Closed Captioning(also: CC, Closed Captions)

Text displayed on a screen that transcribes spoken dialogue, identifies speakers, and describes relevant sound effects in video content. Unlike open captions which are permanently embedded in the video, closed captions can be toggled on or off by the viewer. Closed captioning is…

Cognitive Accessibility Guidelines(also: COGA, Making Content Usable for People with Cognitive and Learning Disabilities)

W3C guidance for making web content accessible to people with cognitive and learning disabilities, including intellectual disabilities, autism, dementia, ADHD, dyslexia, and dyscalculia. Published as a W3C Working Draft, COGA provides design patterns for supporting users in…

Cognitive accessibility(also: Cognitive a11y, COGA)

The practice of designing digital content, interfaces, and interactions so they are usable by people with cognitive, learning, and neurological disabilities, including conditions such as dementia, intellectual disabilities, attention deficit disorders, and learning disabilities.…

Colour Contrast(also: Color Contrast, Contrast Ratio)

The measurable difference in luminance or colour between two adjacent elements, used to determine readability and visual distinguishability. WCAG defines minimum contrast ratios (4.5:1 for normal text, 3:1 for large text at AA level) based on relative luminance calculations…

Colour contrast ratio(also: Contrast ratio, Luminance contrast ratio, Color contrast)

A numerical measure of the perceived brightness difference between a foreground colour (typically text) and its background, expressed as a ratio ranging from 1:1 (no contrast, identical colours) to 21:1 (maximum contrast, black on white). WCAG defines minimum contrast ratios to…

Conformance Evaluation(also: Conformance Assessment, Accessibility Conformance Testing)

The process of systematically assessing whether a website, application, or digital product meets the requirements of a specific accessibility standard, typically WCAG at a designated conformance level (A, AA, or AAA). Conformance evaluation typically combines automated testing…

Conformance Level(also: WCAG Level, Priority Level)

The three-tiered classification system used by WCAG to rank success criteria by their importance and impact on accessibility. Level A represents the minimum baseline — criteria that must be met or some users will be completely unable to access content. Level AA addresses the…

Conformance Review(also: WCAG Conformance Review, Conformance Evaluation, Accessibility Conformance Review)

A conformance review is a systematic evaluation of a website or web application against a specific set of accessibility guidelines, most commonly WCAG, to determine whether and to what level the content meets the standard's success criteria. The review process involves checking…

Content Dictionary(also: CD, OpenMath Content Dictionary)

A formal specification in the OpenMath standard that provides the definition, description, and properties of a collection of related mathematical symbols. Each Content Dictionary defines symbols used in a particular mathematical domain (such as arithmetic, linear algebra, or…

Dexter Model(also: Dexter Hypertext Reference Model)

A reference model for hypertext systems published in 1988 that defines the fundamental concepts of components, links, anchors, and presentation specifications. The Dexter Model was created as a superset description of what hypertext systems could be, with individual systems like…

Document accessibility(also: Accessible documents)

The practice of creating digital documents (PDFs, Word files, presentations, spreadsheets) that can be read and navigated by people using assistive technologies. Key requirements include semantic structure tags, logical reading order, alternative text for images, marked table…

EARL(also: Evaluation and Report Language)

A machine-readable format developed by the W3C for expressing the results of accessibility evaluations in a standardized way. EARL uses RDF (Resource Description Framework) to describe test results including the outcome (pass, fail, cannot tell, inapplicable, untested), the test…

EN 301 549(also: European accessibility standard)

The European standard for accessibility requirements of ICT products and services, harmonized under the European Accessibility Act. EN 301 549 covers web content, software, hardware, and documentation, incorporating WCAG 2.1 Level AA for web and non-web documents while adding…

European Accessibility Act(also: EAA, Directive 2019/882)

A European Union directive adopted in 2019 that establishes common accessibility requirements for key products and services across EU member states. The EAA covers computers, smartphones, ATMs, e-commerce, banking services, e-books, and electronic communications, among others.…

FAIR Principles(also: FAIR Data Principles, Findable Accessible Interoperable Reusable)

The FAIR Principles are a set of guidelines for making digital data and resources Findable, Accessible, Interoperable, and Reusable. Developed by an international consortium and published in 2016, they are widely adopted in research, libraries, and cultural heritage…

Focus trap(also: Keyboard trap, Focus lock)

A web accessibility barrier in which keyboard focus becomes confined to a particular element or region of a page, preventing the user from navigating away using standard keyboard commands. Focus traps are especially problematic for screen reader users and keyboard-only users,…

Font Embedding(also: Embedded Fonts, PDF Font Embedding)

The practice of including the complete font data within a PDF document so that the text can be accurately rendered and read regardless of whether the font is installed on the viewer's system. Font embedding is an accessibility requirement because non-embedded fonts can cause…