Glossary

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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…

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