Glossary

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Section 508(also: 508 Compliance, Rehabilitation Act Section 508)

A provision of the United States Rehabilitation Act that requires federal agencies to make their electronic and information technology accessible to people with disabilities. Updated in 2017 (the "Section 508 Refresh"), the standards now incorporate WCAG 2.0 Level AA as the…

Semantic Tagging(also: Structural Tagging, PDF Semantic Markup)

The process of marking up content within a PDF document with tags that convey the semantic meaning and structural role of each element — such as headings, paragraphs, lists, tables, figures, and links — rather than just visual formatting. Proper semantic tagging ensures that…

Sensory Characteristics(also: WCAG 1.3.3, Success Criterion 1.3.3)

WCAG 2.1 Success Criterion 1.3.3 (Level A), which requires that instructions for understanding and operating content not rely solely on sensory characteristics such as shape, colour, size, visual location, orientation, or sound. Examples that violate 1.3.3 include referring to…

Stanca Act(also: Legge Stanca, Italian Accessibility Law, Law 4/2004)

The Stanca Act (Legge Stanca, Law No. 4 of January 9, 2004) is Italy's primary legislation mandating digital accessibility for public sector websites and services. Named after Lucio Stanca, the Minister for Innovation and Technologies who championed it, the law requires that…

Success Criteria(also: Success Criterion, SC)

The testable statements within the Web Content Accessibility Guidelines (WCAG) that define specific requirements for making web content accessible. Each success criterion is assigned a conformance level (A, AA, or AAA) indicating its priority. Success criteria are…

Tag Tree(also: PDF Tag Structure, Structure Tree, Tagged PDF Structure)

The hierarchical structure of semantic tags embedded within a PDF document that defines the logical organization and reading order of its content. A tag tree is analogous to the DOM (Document Object Model) in HTML — it identifies headings, paragraphs, lists, tables, figures, and…

Tagged PDF(also: Structured PDF, Accessible PDF)

A PDF document that contains semantic structure tags defining the logical reading order, headings, paragraphs, lists, tables, and figures — enabling screen readers and other assistive technologies to navigate and interpret the content meaningfully. Without tags, a PDF is…

Testability(also: Reliably Human Testable, Machine Testable)

In the context of accessibility standards, testability refers to the degree to which a guideline or success criterion can be evaluated with consistent, reproducible results — either through automated tools (machine testable) or through human inspection where at least 80% of…

UAAG(also: User Agent Accessibility Guidelines)

A set of guidelines from the W3C Web Accessibility Initiative that explains how to make user agents — browsers, media players, and other applications that render web content — accessible to people with disabilities. UAAG addresses how user agents should support assistive…

UWEM(also: Unified Web Evaluation Methodology)

The Unified Web Evaluation Methodology (UWEM) is a standardized European methodology for evaluating web accessibility conformance with WCAG. Developed through EU-funded projects including the European Internet Accessibility Observatory (EIAO) and Support-EAM, UWEM provides…

Unified English Braille(also: UEB)

The standard braille code used for English-language literary materials in the United States, United Kingdom, Australia, Canada, and other English-speaking countries. UEB was adopted to replace multiple competing braille codes with a single unified system, providing consistent…

Unified Web Evaluation Methodology(also: UWEM)

A standardized methodology developed by the European Web Accessibility Benchmarking Cluster (WAB Cluster) for evaluating the accessibility of websites in a consistent, comparable way. UWEM provides formulas for calculating quantitative accessibility scores from WCAG checkpoint…

User Agent(also: Browser, Web Browser)

In web accessibility, a user agent is any software that retrieves, renders, and facilitates user interaction with web content. This includes mainstream web browsers like Chrome, Firefox, and Safari, as well as assistive technologies such as screen readers that work alongside…

User Agent Accessibility Guidelines(also: UAAG)

W3C guidelines that explain how to make user agents—web browsers, media players, and other applications that render web content—accessible to people with disabilities. UAAG covers how user agents should support accessibility features built into web content, provide their own…

VPAT(also: Voluntary Product Accessibility Template, Accessibility Conformance Report, ACR)

A standardized document in which vendors report how well their product or service conforms to accessibility standards such as WCAG, Section 508, and EN 301 549. Originally created by the Information Technology Industry Council (ITI), VPATs help procurement teams assess the…

Verbatim Captioning(also: Verbatim Captions)

A captioning approach that reproduces every spoken word exactly as uttered, including filler words, false starts, and repetitions. Regulators in many countries (e.g., the Canadian CRTC, the US FCC) emphasize verbatim accuracy as a quality requirement. Verbatim captions preserve…

Verifiable Credential(also: VC)

A cryptographically signed statement about a person, organisation, or object that a relying party can verify without contacting the issuer, following the W3C Verifiable Credentials Data Model. Verifiable credentials are the underlying data format used by identity wallets, and…

Voice over LTE(also: VoLTE, LTE Voice, HD Voice)

A standard for transmitting voice calls over 4G LTE mobile networks using IP-based protocols rather than legacy circuit-switched networks. VoLTE typically uses the AMR-WB codec, enabling wideband HD voice quality that significantly benefits people with hearing loss. The improved…

W3C(also: World Wide Web Consortium)

The main international standards organisation for the World Wide Web, founded by Tim Berners-Lee in 1994. The W3C develops and maintains specifications including HTML, CSS, SVG, and ARIA. Its Web Accessibility Initiative (WAI) is responsible for the Web Content Accessibility…

WAI(also: Web Accessibility Initiative)

A programme of the World Wide Web Consortium (W3C) that develops strategies, standards, and supporting resources to make the web accessible to people with disabilities. WAI is responsible for producing some of the most widely adopted accessibility standards, including the Web…

WCAG(also: Web Content Accessibility Guidelines, WCAG 1.0, WCAG 2.0)

A set of guidelines published by the W3C Web Accessibility Initiative (WAI) that define how to make web content more accessible to people with disabilities. WCAG is organized around four principles: Perceivable, Operable, Understandable, and Robust (POUR). The current version in…

WCAG 2.4 Navigable(also: Guideline 2.4, Navigable Guideline)

A guideline within the Web Content Accessibility Guidelines (WCAG) under the Operable principle that requires web content to provide ways to help users navigate, find content, and determine where they are. Its success criteria address bypass blocks (skip navigation links), page…

WCAG Compliance(also: WCAG Conformance, Web Accessibility Compliance)

The degree to which a website or web application meets the requirements specified in the Web Content Accessibility Guidelines (WCAG). WCAG defines three conformance levels (A, AA, AAA) with increasingly stringent criteria. Full WCAG compliance is rare — large-scale audits find…

WCAG Conformance(also: WCAG Compliance, Web Accessibility Conformance)

The degree to which a website or web application meets the requirements defined in the Web Content Accessibility Guidelines (WCAG). WCAG defines three conformance levels: Level A (minimum, addressing the most critical barriers), Level AA (the standard target for most regulations…

WCAG Conformance Levels(also: WCAG Levels, Level A, Level AA)

WCAG defines three levels of conformance that indicate the degree to which web content meets accessibility requirements. Level A is the minimum, addressing the most critical barriers that would completely prevent some users from accessing content. Level AA is the target for most…

WCAG-EM(also: Website Accessibility Conformance Evaluation Methodology)

A structured methodology published by the W3C for evaluating how well a website conforms to the Web Content Accessibility Guidelines (WCAG). WCAG-EM defines a five-step process: defining the evaluation scope, exploring the website, selecting a representative sample of pages,…

WHODAS 2.0(also: WHODAS, WHO Disability Assessment Schedule, World Health Organization Disability Assessment Schedule 2.0)

WHODAS 2.0 is the World Health Organization Disability Assessment Schedule, version 2.0, a standardized instrument that measures health and disability across six life domains: cognition, mobility, self-care, getting along with others, life activities, and participation in…

Web Accessibility Directive(also: WAD, Directive 2016/2102)

A European Union directive adopted in 2016 requiring all public sector bodies in EU member states to make their websites and mobile applications accessible. The directive mandates compliance with EN 301 549 (which incorporates WCAG 2.1 AA) and requires public sector…

Web Accessibility Initiative(also: WAI)

A program of the World Wide Web Consortium (W3C) that develops strategies, standards, and supporting resources to make the web accessible to people with disabilities. Founded in 1997, WAI is responsible for producing the Web Content Accessibility Guidelines (WCAG), the Authoring…

Web Compliance Engineering

A discipline within Web Engineering focused on the application of quality assurance, testing, and management processes to ensure that web applications conform to standards, policy environments, and other quality criteria such as accessibility requirements. Web Compliance…

Wheelchair Accessibility(also: Wheelchair Access, Wheeled Mobility Access)

The degree to which physical environments, facilities, and services can be used by people who use wheelchairs. Wheelchair accessibility encompasses a wide range of factors including doorway widths, ramp availability and slope, floor surfaces, turning radius clearances, table and…

World-Readiness Standards for Learning Languages(also: ACTFL World-Readiness Standards, WRSLL, 5 Cs of Foreign Language Education)

A set of US national standards for language education published by the American Council on the Teaching of Foreign Languages (ACTFL). The standards are organised around five goal areas — Communication, Cultures, Connections, Comparisons, and Communities (the "5 Cs") — and apply…

XR Accessibility User Requirements(also: XAUR)

A W3C document that provides accessibility guidelines and user requirements specifically for extended reality (XR) applications, including virtual reality, augmented reality, and mixed reality. XAUR identifies the diverse needs of users with disabilities in XR environments and…

eMAG(also: Modelo de Acessibilidade em Governo Eletrônico, Brazilian Digital Accessibility Model)

The Brazilian government's digital accessibility model (Modelo de Acessibilidade em Governo Eletrônico) that provides mandatory guidelines for how government websites must ensure accessibility and eliminate access barriers. Based on WCAG 2.0, eMAG covers all Level A and AA…

ePrivacy Directive(also: Cookie Directive, EU Cookie Law, Directive 2002/58/EC)

A European Union directive that complements GDPR by specifically addressing privacy in electronic communications, including the use of cookies and similar tracking technologies. The directive requires websites to obtain informed consent before storing cookies on user devices.…