WAI Glossary

AI

ASCII art

picture created by a spatial arrangement of characters or glyphs (typically from the 95 printable characters defined by ASCII)

Accessibility API

• accessibility api
• accessibility apis

Operating systems and other platforms provide a set of interfaces that expose information about objects and events to assistive technologies. Assistive technologies use these interfaces to get information about and interact with those widgets. Examples of accessibility APIs are Microsoft Active Accessibility [[MSAA]], Microsoft User Interface Automation [[UI-AUTOMATION]], MSAA with UIA Express [[UIA-EXPRESS]], the Mac OS X Accessibility Protocol [[AXAPI]], the Linux/Unix Accessibility Toolkit [[ATK]] and Assistive Technology Service Provider Interface [[AT-SPI]], and IAccessible2 [[IAccessible2]].

Accessibility Subtree

An accessible object in the accessibility tree and its descendants in that tree. It does not include objects which have relationships other than parent-child in that tree. For example, it does not include objects linked via aria-flowto unless those objects are also descendants in the accessibility tree.

Accessibility Tree

Tree of accessible objects that represents the structure of the user interface (UI). Each node in the accessibility tree represents an element in the UI as exposed through the accessibility API ; for example, a push button, a check box, or container.

Accessible Description

An accessible description provides additional information, related to an interface element, that complements the accessible name. The accessible description might or might not be visually perceivable.

Accessible Name

• accessible name
• accessible names

The accessible name is the name of a user interface element. Each platform accessibility API provides the accessible name property. The value of the accessible name may be derived from a visible (e.g., the visible text on a button) or invisible (e.g., the text alternative that describes an icon) property of the user interface element. See related accessible description.

A simple use for the accessible name property may be illustrated by an "OK" button. The text "OK" is the accessible name. When the button receives focus, assistive technologies may concatenate the platform's role description with the accessible name. For example, a screen reader may speak "push-button OK" or "OK button". The order of concatenation and specifics of the role description (e.g., "button", "push-button", "clickable button") are determined by platform accessibility APIs or assistive technologies.

Accessible Name

The accessible name is the programmatically determined name of a user interface element that is included in the accessibility tree.

The accessible name is calculated using the accessible name and description computation.

For native markup languages, such as HTML and SVG, additional information on how to calculate the accessible name can be found in HTML Accessibility API Mappings 1.0, Accessible Name and Description Computation (working draft) and SVG Accessibility API Mappings, Name and Description (working draft).

For more details, see examples of accessible name.

Note: As per the accessible name and description computation, each element always has an accessible name. When no accessible name is provided, the element will nonetheless be assigned an empty ("") one.

Note: As per the accessible name and description computation, accessible names are flat string trimmed of leading and trailing whitespace. Notably, it is not possible for a non-empty accessible name to be composed only of whitespace since these must be trimmed.

Accessibility Support for Accessible Name

• Because the accessible name and description computation is not clear about which whitespace are considered, browsers behave differently when trimming and flattening the accessible name. For example, some browsers completely trim non-breaking spaces while some keep them in the accessible name.
• There exists a popular browser which does not perform the same trimming and flattening depending whether the accessible name comes from content, an aria-label attribute, or an alt attribute.
• There exists a popular browser which assign no accessible name (null) when none is provided, instead of assigned an empty accessible name ("").
• The accessible name and description computation suggest that if an aria-labelledby attribute refers to an existing but empty element, the computation should stop and return an empty name without defaulting to the next steps. Several user agents and assistive technologies chose to use the next step in the computation in this case.

Accessible object

• accessible object
• accessible objects

A node in the accessibility tree of a platform accessibility API . Accessible objects expose various states, properties, and events for use by assistive technologies. In the context of markup languages (e.g., HTML and SVG) in general, and of WAI-ARIA in particular, markup elements and their attributes are represented as accessible objects.

Activation behavior

The action taken when an event, typically initiated by users through an input device, causes an element to fulfill a defined role. The role may be defined for that element by the host language, or by author-defined variables, or both. The role for any given element may be a generic action, or may be unique to that element. For example, the activation behavior of an HTML or SVG <a> element shall be to cause the user agent to traverse the link specified in the href attribute, with the further optional parameter of specifying the browsing context for the traversal (such as the current window or tab, a named window, or a new window); the activation behavior of an HTML <input> element with the type attribute value submit shall be to send the values of the form elements to an author-defined IRI by the author-defined HTTP method.

Adjectival rating

• Adjective-based
• Adjectival
• Adjectival rating

A system to report evaluation results as a set of human-understandable adjectives which represent groupings of scores.

Age Related Forgetfulness

• Age Appropriate Forgetfulness
• age-related forgetfulness

Sometimes called "Age Appropriate Forgetfulness" or "Age Related Memory Loss".

People with age related forgefulness have impaired memory issues that can be a normal part of healthy aging. They may take longer to learn new things, forget something but remember it later, or occasionally forget particular words. (This differs from dementia where forgetfulness is due to a disorder and is more pronounced.)

Alternative and Augmentative Communication System

• AAC

Sometimes called “AAC”.

Any method, device, or application that can be used to help those who cannot use spoken language and need additional support by means of symbols, images, and/or text. For example, a screen with symbols that the user can select to speak the appropriate words or add them to a document.

Anxiety Disorders

People who have anxiety disorders struggle with intense and uncontrollable feelings of anxiety, fear, worry, and/or panic. This is more than just feeling worried once in a while. This may last for a long time and can interfere with daily activities, such as concentration and executive function.

Appropriate field for the form control

The field name of the form control is appropriate if it is listed in the autocomplete fields table from the HTML 5.2 specification as applying to the specified control group. https://html.spec.whatwg.org/#inappropriate-for-the-control.

Assistive Technologies

• assistive technology

Hardware and/or software that:

• relies on services provided by a user agent to retrieve and render Web content
• works with a user agent or web content itself through the use of APIs, and
• provides services beyond those offered by the user agent to facilitate user interaction with web content by people with disabilities

This definition may differ from that used in other documents.

Examples of assistive technologies that are important in the context of this document include the following:

• screen magnifiers, which are used to enlarge and improve the visual readability of rendered text and images;
• screen readers, which are most-often used to convey information through synthesized speech or a refreshable Braille display;
• text-to-speech software, which is used to convert text into synthetic speech;
• speech recognition software, which is used to allow spoken control and dictation;
• alternate input technologies (including head pointers, on-screen keyboards, single switches, and sip/puff devices), which are used to simulate the keyboard;
• alternate pointing devices, which are used to simulate mouse pointing and clicking.

Attention Deficit (Hyperactivity) disorder, AD(H)D

• Attention deficit disorder
• ADD
• Attention deficit hyperactivity disorder
• AD(H)D
• Attention Deficit Hyperactive Disorder
• Attention Deficit (Hyperactivity) disorder

Sometimes called “attention deficit disorder”, “ADD”, and “attention deficit hyperactivity disorder”, “ADHD”.

Attention deficit (hyperactivity) disorder or AD(H)D involves difficulty focusing on a single task, focusing for longer periods, or being easily distracted. It is marked by an ongoing pattern of inattention and/or hyperactivity-impulsivity that interferes with functioning or development.

Attribute

• attribute
• attributes

In this specification, attribute is used as it is in markup languages. Attributes are structural features added to elements to provide information about the states and properties of the object represented by the element.

Attribute value

The attribute value of a content attribute set on an HTML element is the value that the attribute gets after being parsed and computed according to specifications. It may differ from the value that is actually written in the HTML code due to trimming whitespace or non-digits characters, default values, or case-insensitivity.

Some notable case of attribute value, among others:

• For enumerated attributes, the attribute value is either the state of the attribute, or the keyword that maps to it; even for the default states. Thus <input type="image" /> has an attribute value of either Image Button (the state) or image (the keyword mapping to it), both formulations having the same meaning; similarly, "an input element with a type attribute value of Text" can be either <input type="text" />, <input /> (missing value default), or <input type="invalid" /> (invalid value default).
• For boolean attributes, the attribute value is true when the attribute is present and false otherwise. Thus <button disabled>, <button disabled="disabled"> and <button disabled=""> all have a disabled attribute value of true.
• For attributes whose value is used in a case-insensitive context, the attribute value is the lowercase version of the value written in the HTML code.
• For attributes that accept numbers, the attribute value is the result of parsing the value written in the HTML code according to the rules for parsing this kind of number.
• For attributes that accept sets of tokens, whether space separated or comma separated, the attribute value is the set of tokens obtained after parsing the set and, depending on the case, converting its items to lowercase (if the set is used in a case-insensitive context).
• For aria-* attributes, the attribute value is computed as indicated in the WAI-ARIA specification and the HTML Accessibility API Mappings.

This list is not exhaustive, and only serves as an illustration for some of the most common cases.

The attribute value of an IDL attribute is the value returned on getting it. Note that when an IDL attribute reflects a content attribute, they have the same attribute value.

Audio output

This test aspect includes all auditory data output from the web page into an audio channel.

Autistic

• Autism spectrum disorder
• ASD
• autism
• asperger syndrome
• pervasive developmental disorder

Sometimes called “autism spectrum disorder”, “ASD”, “autism”, “asperger syndrome”, and “pervasive developmental disorder”.

Autistic people have some degree of impaired social behavior, communication and language abilities. This may also impact the person’s ability to regulate behavior and attention. Individuals can have a narrow range of interests and activities and they may rely on alternative communication methods. Some individuals may also experience episodes of sensory overload. See neurodiversity for an alternative approach to autism and learning and cognitive disabilities.

Automated evaluation

• Automated
• Automatically evaluated
• Automated testing
• Automatically tested

Evaluation conducted using software tools, typically evaluating code-level features and applying heuristics for other tests.

Automated testing is contrasted with other types of testing that involve human judgement or experience. Semi-automated evaluation allows machines to guide humans to areas that need inspection. The emerging field of testing conducted via machine learning is not included in this definition.

Background Colors Of Text

The colors of all pixels, excluding the foreground colors pixels, in the bounding box around a visible character in a text node.

Bayesian filter

• Bayesian filter
• Bayesian filtering

Block of content

A block of content in an HTML web page is a set of nodes from that page for which all the following are true:

• content: there is at least one node which is perceivable content in the block; and
• continuity: if two nodes are in the block, then any node between them (in tree order) is also in the block; and
• downward closure: if a node is in the block, then all its descendants are also in the block; and
• parent closure: if all children of a node are in the block, then this node is also in the block.

Assumptions for Block of content

Block of repeated content

A block of content B, inside an HTML web page P, is a block of repeated content if both the following are true:

• distance 1: there exist an instrument in P which leads the user to another HTML web page P' whose URL has a different host, port (including default port for special URL), or path; and
• repeated: there exist a block of content in P' which is equivalent to B.

Background for Block of repeated content

Blocked event

A blocked event makes no changes to the content of the web page.

Bounding Box around Text

The smallest rectangle that encloses all the visible pixels of a character (including anti-aliased pixels), plus one pixel on every edge (top, right, bottom, left), aligned on the horizontal and vertical axis.

Brain Injury

Brain injury including, traumatic brain injury (TBI) and acquired brain injury (ABI), are caused by damage to the brain which can lead to long-term impairment of executive function, memory, learning, coordination, speech, and emotions as well as other physical and sensory impairments.

Brain injury can have many different causes such as a concussion or stroke, and can happen at any stage of life.

CAPTCHA

• CAPTCHA
• Completely Automated Public Turing Test to Tell Computers and Humans Apart

CAPTCHA

initialism for "Completely Automated Public Turing test to tell Computers and Humans Apart"

CAPTCHA tests often involve asking the user to type in text that is displayed in an obscured image or audio file.

A Turing test is any system of tests designed to differentiate a human from a computer. It is named after famed computer scientist Alan Turing. The term was coined by researchers at Carnegie Mellon University.

CSS pixel

• CSS pixels

visual angle of about 0.0213 degrees

A CSS pixel is the canonical unit of measure for all lengths and measurements in CSS. This unit is density-independent, and distinct from actual hardware pixels present in a display. User agents and operating systems should ensure that a CSS pixel is set as closely as possible to the CSS Values and Units Module Level 3 reference pixel [[!css3-values]], which takes into account the physical dimensions of the display and the assumed viewing distance (factors that cannot be determined by content authors).

Changes in content

A event originated change in the content of a web page occurs when, by comparing the web page before and 1 minute after the event firing, at least one of the following occurs:

• visible changes: the rendered pixels change in any part of the document that is currently within the viewport or that can be brought into the viewport via scrolling; or
• accessibility tree changes: any state, property or event of a node representing an accessible object of the accessibility tree changes, or any node is inserted in, or removed from the accessibility tree; or
• audible changes: the audio rendered by the web page changes.
• If the web page is rendering time-based media, rendered pixels and audio will be changing as part of the playback. The comparison in this instance should compare the pixels and audio that are rendered if the event is not fired, with the ones that are rendered if the event is fired.

Assumptions:

• This definition assumes that there are no changes in the content of the web page caused by another event. If this is not the case, changes may be attributed to the wrong event.
• This definition assumes that the changes happen within a 1 minute time span after the event firing and therefore the comparison between the page before and after the event firing can be made at any time after that time span elapses. If there are changes after this time span, this definition may not detect them. The arbitrary 1 minute time span, selected so that testing this rule would not be impractical, is not included in WCAG.

Class

• class
• classes

A set of instance objects that share similar characteristics.

Clearly labeled location

Secondary information and alternative controls of functionality are often not displayed together with primary information or functionality. For example, an option to change a web page to dark mode may be placed on an options page instead of being available on every page and page state of a website. Another example is a maps application, where, instead of using GPS, an option is available in a dropdown menu to set the current location of the device. Such content should be placed in a clearly labeled location.

The location of a target is said to be clearly labeled when the target can be found by activating "identifiable" instruments which either lead the user to find the target, or to another page or page state from which this action can be repeated until the target is found.

Whether or not the content is "clearly labeled" depends on the starting point of the search. If page A has a link which clearly "identifies" some piece of content, then the location of the content is clearly labeled. Page B, which can be in the same website, may not have such a link or may have a link with a link text that does not "identify" target content or which can be interpreted to "identify" more than one target, and so the location of the content starting from page B is not clearly labeled.

For the purpose of this definition, an instrument is identifiable if any text or other content with a text alternative, allows any user to identify an element with a semantic role that inherits from widget.

A web page changes state when the document's body changes without a change in the document's URL.

Clipped by Overflow

A node with an ancestor in the flat tree with a computed overflow of none or clipped, where changing the overflow of all such ancestors to visible would cause more of the node to become visible.

Example of clipped by overflow for Clipped by Overflow

This img element has an ancestor div element with an overflow of none (both overflow-x and overflow-y). The height of the img is greater than that of the ancestor div, and so is clipped by the overflow property of the div.

                           
                              
                                 
                                    <div
                                 
                                    style
                                    
                                       =
                                       "
                                       
                                          height
                                          : 100px;
                                          overflow
                                          : none;
                                       
                                       "
                                    
                                 
                                 >
                              
                              
                                 
                                    <img
                                 src
                                 
                                    =
                                    "/test-assets/w3c-logo.png"
                                 
                                 height
                                 
                                    =
                                    "150"
                                 
                                 alt
                                 
                                    =
                                    "Partial W3C Logo"
                                 
                                 />
                              
                              
                                 
                                    </div
                                 >
                              
                           
                        

Cognitive and Learning Disabilities

• cognitive disabilities
• learning disabilities
• LD
• intellectual disabilities
• specific learning disabilities

May include: cognitive disabilities, learning disabilities (LD), intellectual disabilities and specific learning disability.

Cognitive disabilities and learning disabilities can mean different things in different locations. Taken together they refer to:

• significantly reduced ability in one or more areas of cognitive function that affect learning, such as communication, reading, writing, or math. Note overall intelligence is often not affected and people may function any level in other areas of learning. (Sometimes called learning disability or specific learning disability), and / or
• significantly reduced ability to understand new or complex information and learn new skills, with a reduced ability to cope independently. (Sometimes called cognitive disability, learning disability or intellectual disability), and / or
• significantly reduced memory and attention or visual, language, or numerical thinking.

Cognitive function test

• cognitive function test

New

A task that requires the user to remember, manipulate, or transcribe information. Examples include, but are not limited to:

• memorization, such as remembering a username, password, set of characters, images, or patterns. The common identifiers name, e-mail, and phone number are not considered cognitive function tests as they are personal to the user and consistent across websites;
• transcription, such as typing in characters;
• use of correct spelling;
• performance of calculations;
• solving of puzzles.

Conformance

• Conform

Satisfying all the requirements of the guidelines. Conformance is an important part of following the guidelines even when not making a formal Conformance Claim.

See Conformance.

Correct autocomplete field

Any field name listed in the autocomplete fields table from the HTML 5.2 specification: https://html.spec.whatwg.org/#autofill-field

Critical error

• Critical errors
• Critical failure
• Critical failures

An accessibility problem that will stop a user from being able to complete a process.

Critical errors include:

• Items that will stop a user from being able to complete the task if it exists anywhere on the view (examples: flashing, keyboard trap, audio with no pause);
• Errors that when located within a process means the process cannot be completed (example: submit button not in tab order);
• Errors that when aggregated within a view or across a process cause failure (example: a large amount of confusing, ambiguous language).

DOMString

Default Page Language

The default language of a web page is the most common language of its top-level browsing context document, if it is unique. If this document has either no or several most common languages, then it has no default language.

For more details, see examples of default language.

Deprecate

• deprecated

To declare something outdated and in the process of being phased out, usually in favor of a specified replacement.

Deprecated documents are no longer recommended for use and may cease to exist in the future.

Deprecated

• deprecated
• deprecate
• deprecation

A deprecated role, state, or property is one which has been outdated by newer constructs or changed circumstances, and which may be removed in future versions of the WAI-ARIA specification. User agents are encouraged to continue to support items identified as deprecated for backward compatibility. For more information, see Deprecated Requirements in the Conformance section.

Desktop focus event

• desktop focus
• desktop focus events

Event from/to the host operating system via the accessibility API, notifying of a change of input focus.

Disabled Element

An element is disabled when it has been rendered inoperable in one or more of the following ways:

1. The element matches the :disabled pseudo-class. For HTML elements this means that the element is actually disabled.
2. The element has a shadow-including ancestor whose aria-disabled attribute value is "true".

Assumptions for Disabled Element

This definition assumes that when the aria-disabled attribute is specified on an element, this element has also been disabled for users that do not rely on assistive technology. For example, this can be done by disabling pointer events using the pointer-events property and by disabling keyboard interactions using the tabindex attribute. If this is not the case, the definition will produce incorrect results.

Early Stage Dementia

Common impairments of early stage dementia include memory loss, difficulty concentrating, and struggling to follow a conversation or find the right word. These may appear before a diagnosis of dementia. At this stage, these symptoms are often mild.

Easy to Understand Language

• Easy Reading
• Easy To Read
• Plain Language
• Easy To Understand

Sometimes called: “easy reading”, “easy to read”, “plain language”, “easy to understand”.

Easy to Understand Language refers to text content that is in an accessible, easy to understand, form. It is often useful for people with learning disabilities, and is easier for many other people as well.

Element

• element
• elements
• element's

In this specification, element is used as it is in markup languages. Elements are the structural elements in markup language that contains the data profile for objects.

Embedded Image

An element presents an embedded image when any of the following is true:

• the element is an img element with a non-empty source set; or
• the element is an input element with a type attribute value of image and its src attribute value is not empty; or
• the element is an object element with a data attribute value referencing a resource with an image MIME type; or
• the element is an svg element having one or more image descendants with a non-empty href attribute value; or
• the element has a computed background-image CSS property with at least one image that is a url reference.

Equivalent resource

Non-identical resources can still be equivalent resources by equally complying to the expectation formed by the user when navigating to them, thus serving an equivalent purpose. This would usually involve that the advertised key content is the same.

Web pages and documents (e.g. PDFs, office formats etc.) may be equivalent resources, even if the resources:

• are located on different URLs, including different domains
• present different navigation options, e.g. through bread crumbs or local sub menus
• contain different amounts of information and/or differently worded information
• use different layouts.

If all resources cover the user's expectations equally well, the resources are considered to be equivalent.

Note: The user's expectations for the resource can be formed by different things, e.g. the name of the link leading to the resource, with or without the context around the link. This depends on the accessibility requirement that is tested.

Note: If the same content is presented in different formats or languages, the format or language itself is often part of the purpose of the content, e.g. an article as both HTML and PDF, an image in different sizes, or an article in two different languages. If getting the same content in different formats or languages is the purpose of having separate links, the resources are not equivalent.

Evaluation

Event

• event
• events

A programmatic message used to communicate discrete changes in the state of an object to other objects in a computational system. User input to a web page is commonly mediated through abstract events that describe the interaction and can provide notice of changes to the state of a document object. In some programming languages, events are more commonly known as notifications.

Executive Function

• executive functioning
• executive functions

The group of cognitive processes and skills required for planning, fulfilling tasks, and goals. It includes working memory and remembering details, impulse inhibition, organizing tasks, managing time, fluid reasoning, and solving problems.

Explicit Semantic Role

The explicit semantic role of an element is determined by its role attribute (if any).

The role attribute takes a list of tokens. The explicit semantic role is the first valid role in this list. The valid roles are all non-abstract roles from WAI-ARIA Specifications. If the element has no role attribute, or if it has one with no valid role, then this element has no explicit semantic role.

Other roles may be added as they become available. Not all roles will be supported in all assistive technologies. Testers are encouraged to adjust which roles are allowed according to the accessibility support base line. For the purposes of executing test cases in all rules, it should be assumed that all roles are supported by assistive technologies so that none of the roles fail due to lack of accessibility support.

Accessibility Support for Explicit Semantic Role

Some browsers and assistive technologies treat the tokens of the role attribute as case-sensitive. Unless lowercase letters are used for the value of the role attribute, not all user agents will be able to interpret the tokens correctly. ARIA in HTML (working draft) also specifies that authors must use lowercase letters for the role and aria-* attributes.

Expose

Translated to platform-specific accessibility APIs as defined in the Core Accessibility API Mappings.

Filename

A filename is a text string that identifies an electronically stored file. In a URL it is located at the end of the path, after the last slash and before any query strings. For example the src attribute specifies a URL path of src="/foo/bar.jpg?baz " which contains the filename bar.jpg.

Focusable

Elements that can become the target of keyboard input as described in the HTML specification of focusable and can be focused.

Focused

An element is focused when that element matches the :focus pseudo-class.

Foreground Colors Of Text

The colors of all the pixels of a visible character in a text node that change color when the CSS color property is changed. This includes anti-aliased pixels.

Note: Anti-aliasing is a technique in which the foreground color and background color are blended to create smooth edges.

Form Field Error Indicator

Any text, or non-text content, or an element that has presentation indicating that an error was identified which appears to be related to some user input into, or the lack of user input into some element. These could be different types of errors, for example:

• missing input, for example a required form field that was left empty
• incorrect input, such as an invalid password
• input not in an expected format, expected range, or of an allowed value
• timing error, such as session timeouts or expiration of an allowed action
• authentication or authorization errors

Note: An error indicator can be a separate element in the page, but it can also be part of a form control. For example a red outline on a form control is often used to indicate an error. Not all red outlines are indicators of an error though. This depends on the presentation of the form control in relation to other elements on the page.

Functional category

• Functional categories
• Functional category(ies)

A conceptual grouping of functional needs that represent generalized sets of user groups.

See Functional Categories.

Functional need

• Functional needs

A statement that describes a specific gap in one’s ability, or a specific mismatch between ability and the designed environment or context.

Graphical Document

• graphical document
• graphical documents

A document containing graphic representations with user-navigable parts. Charts, maps, diagrams, blueprints, and dashboards are examples of graphical documents. A graphical document is composed using any combination of symbols, images, text, and graphic primitives (shapes such as circles, points, lines, paths, rectangles, etc).

Guideline

• Guidelines

High-level, plain-language content used to organize outcomes.

See Guidelines in the Explainer.

Hidden

Indicates that the element is not visible, perceivable, or interactive to any user. An element is considered hidden if it or any one of its ancestor elements is not rendered or is explicitly hidden.

Highest Possible Contrast

The highest value of the contrast ratios between two sets of colors.

How-to

• How-tos

Provides explanatory material for each guideline that applies across technologies.

This plain language resource includes information on getting started, who the guideline helps and how, as well as information for designers and developers.

See How-tos in the Explainer.

Human evaluation

• Human testing
• Human evaluated
• Human tested
• Manual
• Manual evaluation
• Manual testing
• Manually tested

Evaluation conducted by a human, typically to apply human judgement to tests that cannot be fully automatically evaluated.

Human evaluation is contrasted with automated evaluation which is done entirely by machine, though it includes semi-automated evaluation which allows machines to guide humans to areas that need inspection. Human evaluation involves inspection of content features, by contrast with user testing which directly tests the experience of users with content.

Implicit Semantic Role

The implicit semantic role of an element is a pre-defined value given by the host language which depends on the element and its ancestors.

Implicit roles for HTML and SVG, are documented in the HTML accessibility API mappings (working draft) and the SVG accessibility API mappings (working draft).

Accessibility Support for Implicit Semantic Role

• Images with an empty alt attribute should have an implicit role of presentation, according to the HTML Accessibility API Mapping (work in progress). However, there are several popular browsers that do not treat images with empty alt attribute as having a role of presentation. Instead, they add the img element to the accessibility tree with a role of either img or graphic.

Included in the accessibility tree

Elements included in the accessibility tree of platform specific accessibility APIs. Elements in the accessibility tree are exposed to assistive technologies, allowing users to interact with the elements in a way that meet the requirements of the individual user.

The general rules for when elements are included in the accessibility tree are defined in the core accessibility API mappings. For native markup languages, such as HTML and SVG, additional rules for when elements are included in the accessibility tree can be found in the HTML accessibility API mappings (working draft) and the SVG accessibility API mappings (working draft).

For more details, see [examples of included in the accessibility tree][].

Note: Users of assistive technologies might still be able to interact with elements that are not included in the accessibility tree. An example of this is a focusable element with an aria-hidden attribute with a value of true. Such an element could still be interacted using sequential keyboard navigation regardless of the assistive technologies used, even though the element would not be included in the accessibility tree. [examples of included in the accessibility tree]: https://act-rules.github.io/pages/examples/included-in-the-accessibility-tree/

Informative

• informative
• non-normative

Content provided for information purposes and not required for conformance. Content required for conformance is referred to as normative.

Informative

• Non-normative

Content provided for information purposes and not required for conformance.

Content required for conformance is referred to as normative .

Inheriting Semantic Role

An element with an inheriting semantic role of X is any element with a non-abstract semantic role that inherits from X, or is the same as X.

Example: An "inheriting semantic link" is any element that either has the semantic role of link or a semantic role that inherits from the link role, such as doc-biblioref.

Instrument to achieve an objective

An HTML element that when activated allows an end-user to achieve an objective.

Note: Any rule that uses this definition must provide an unambiguous description of the objective the instrument is used to achieve.

Background About Instrument for Instrument to achieve an objective

This definition is a more restrictive version of WCAG's definition of mechanism, notably restricting it to the current document. WCAG has a note that "The mechanism needs to meet all success criteria for the conformance level claimed." This includes all the level A criteria such as Success Criterion 2.1.1 Keyboard (the mechanism must be keyboard accessible) or Success Criterion 4.1.2 Name, Role, Value (the mechanism must be exposed to assistive technologies and have an accessible name). This definition, and the rules using it, leaves these extra requirements out. This avoids reporting the same component twice for the same reason (e.g., missing an accessible name) under two different rules and Success Criteria, and helps pinpoint the error related to each Success Criterion. Instruments should nonetheless be fully accessible at the correct conformance level (depending on the rule using them).

Interactive Voice Response

• Integrated Voice Menus
• IVR

Interactive voice response (IVR) systems allow the user to interact with a computer system through the use of a telephone keypad and/or audio input. Audio input can include speech, non-speech vocalizations or audio produced by AAC or other devices. Interactive voice response systems are often used to automate tasks by phone and in call centers. IVR systems often use standards such as VoiceXML [[voicexml21]].

Just before a node

A node N is just before a node of perceivable content P if one of the following is true:

• N and P are the same node; or
• N is not perceivable content and there is no node of perceivable content between N and P (in tree order in the flat tree).

Several nodes may be just before a given node, especially if there are several non-perceivable content nodes next to each other.

Keyboard Accessible

Accessible to the user using a keyboard or assistive technologies that mimic keyboard input, such as a sip and puff tube. References in this document relate to WCAG 2.1 Guideline 2.1: Make all functionality available from a keyboard [[WCAG21]].

Landmark

• landmark
• landmarks

A type of region on a page to which the user may want quick access. Content in such a region is different from that of other regions on the page and relevant to a specific user purpose, such as navigating, searching, perusing the primary content, etc.

Large Scale Text

Text nodes with a computed font-size of:

• at least 18 points, or
• at least 14 points and a computed font weight CSS property of 700 or higher.

Live Region

• live region
• live regions

Live regions are perceivable regions of a web page that are typically updated as a result of an external event when user focus may be elsewhere. These regions are not always updated as a result of a user interaction. Examples of live regions include a chat log, stock ticker, or a sport scoring section that updates periodically to reflect game statistics. Since these asynchronous areas are expected to update outside the user's area of focus, assistive technologies such as screen readers have either been unaware of their existence or unable to process them for the user. WAI-ARIA has provided a collection of properties that allow the author to identify these live regions and process them: aria-live, aria-relevant, aria-atomic, and aria-busy.

Managed State

• managed state
• managed states

Accessibility API state that is controlled by the user agent, such as focus and selection. These are contrasted with "unmanaged states" that are typically controlled by the author. Nevertheless, authors can override some managed states, such as aria-posinset and aria-setsize. Many managed states have corresponding CSS pseudo-classes, such as :focus, and pseudo-elements, such as ::selection, that are also updated by the user agent.

Marked as decorative

An element is marked as decorative if one or more of the following conditions is true:

• it has an explicit role of none or presentation; or
• it is an img element with an alt attribute whose value is the empty string (alt=""), and with no explicit role.

Elements are marked as decorative as a way to convey the intention of the author that they are pure decoration. It is different from the element actually being pure decoration as authors may make mistakes. It is different from the element being effectively ignored by assistive technologies as rules such as presentational roles conflict resolution may overwrite this intention.

Elements can also be ignored by assistive technologies if they are programmatically hidden. This is different from marking the element as decorative and does not convey the same intention. Notably, being programmatically hidden may change as users interact with the page (showing and hiding elements) while being marked as decorative should stay the same through all states of the page.

Matching characters

A sequence of characters is considered to match another if, after removing leading and trailing space characters and replacing remaining occurrences of one or more space characters with a single space, the two sequences of characters are equal character-by-character, ignoring any differences in letter casing.

Memory Impairment

Memory impairment refers to an inability to recognize or recall pieces of information or skills that are usually remembered. It can affect:

• Working memory that holds information while it is processed. For example, we rely on working memory for tasks such as copying a number.
• Short-term Memory that stores information for a short time before it is stored in long-term memory. For example, we may rely on short-term memory to remember the location of menus items between web pages.
• Long-term Memory that holds information long term, such as information from personal events, language, and information. For example, we may rely on long-term memory to recall past events.

Mental Health

• Mental health impairment

May include: mental heath impairments.

Mental health refers to our emotional, psychological, and social well-being. A mental health impairment/condition generally has some combination of disturbed thoughts, emotions, and ability to relate to others that impairs daily functioning. Examples include depression, anxiety, and post-traumatic stress disorder. These conditions may cause temporary or long term issues with accessing information, such as difficulty focusing on information, processing information, or understanding it.

Method

• Methods

Detailed information, either technology-specific or technology-agnostic, on ways to meet the outcome as well as tests and scoring information.

See Methods in the Explainer.

Mild Cognitive Impairment (MCI)

• Mild Cognitive Impairment

Mild cognitive impairment (MCI) can involve problems with memory, language, thinking, and judgment that are greater than normal age-related challenges. It is sometimes considered the stage between the common and expected age related forgetfulness and the more serious decline of dementia, although many or most people with MCI will not develop dementia.

Most Common Language of an Element

The most common language of an element is determined by counting the number of words in the text inheriting its programmatic language from this element that are part of any of the languages in the language subtag registry. The same word can be part of multiple languages. In case of ties, the element has several most common languages. If there are no words in the text inheriting its programmatic language from the element, then it has no most common language.

For more details, see examples of most common language.

Namespaced Element

An element with a specific namespaceURI value from HTML namespaces. For example an "SVG element" is any element with the "SVG namespace", which is http://www.w3.org/2000/svg.

Namespaced elements are not limited to elements described in a specification. They also include custom elements. Elements such as a and title have a different namespace depending on where they are used. For example a title in an HTML page usually has the HTML namespace. When used in an svg element, a title element has the SVG namespace instead.

Nemeth Braille

The Nemeth Braille Code for Mathematics is a braille code for encoding mathematical and scientific notation. See Nemeth Braille on Wikipedia.

Neurodiversity

Neurodiversity is a term that refers to the different ways the brain can work and interpret information. It highlights that people naturally think about things differently. Autistic people, attention deficit (hyperactivity) disorder (AD(H)D), dyslexia, and people with other diagnoses or labels may prefer the term “neurodiverse” as they are part of normal and healthy variation in the human population, bringing diverse skills and perspectives.

Node

Basic type of object in the DOM tree or accessibility tree. DOM nodes are further specified as Element or Text nodes, among other types. The nodes of an accessibility tree are accessible objects.

Non-repeated content after repeated content

A node is non-repeated content after repeated content if all the following are true:

• the node is perceivable content; and
• the node is not part of any block of repeated content; and
• the node is after (in tree order in the flat tree) at least one block of repeated content.

Non-streaming media element

A non-streaming media element is an HTML Media Element for which the duration property is not 0.

Normative

Required for conformance. By contrast, content identified as informative or "non-normative" is not required for conformance.

Normative

Content whose instructions are required for conformance.

Content identified as informative or non-normative is never required for conformance.

Object

• object
• objects

In the context of user interfaces, an item in the perceptual user experience, represented in markup languages by one or more elements, and rendered by user agents.

Object

• Objects

An item in the perceptual user experience.

Objects include user interface widgets and identifiable blocks of content.

Ontology

A description of the characteristics of classes and how they relate to each other.

Operable

Usable by users in ways they can control. References in this document relate to WCAG 2.1 Principle 2: Content must be operable [[WCAG21]]. See Keyboard Accessible.

Outcome

• Outcomes

Result of practices that reduce or eliminate barriers that people with disabilities experience.

See Outcomes.

Outcome

An outcome is a conclusion that comes from evaluating an ACT Rule on a test subject or one of its constituent test target. An outcome can be one of the three following types:

• Inapplicable: No part of the test subject matches the applicability
• Passed: A test target meets all expectations
• Failed: A test target does not meet all expectations

Note: A rule has one passed or failed outcome for every test target. When there are no test targets the rule has one inapplicable outcome. This means that each test subject will have one or more outcomes.

Note: Implementations using the EARL10-Schema can express the outcome with the outcome property. In addition to passed, failed and inapplicable, EARL 1.0 also defined an incomplete outcome. While this cannot be the outcome of an ACT Rule when applied in its entirety, it often happens that rules are only partially evaluated. For example, when applicability was automated, but the expectations have to be evaluated manually. Such "interim" results can be expressed with the incomplete outcome.

Owned Element

• owned element
• owned
• owned element's
• owned elements

An 'owned element' is any DOM descendant of the element, any element specified as a child via aria-owns, or any DOM descendant of the owned child.

Owned by

An element A is owned by element B if element A is a child of element B in the accessibility tree.

Being a child in the accessibility tree is different from being a child in the DOM tree. Some DOM nodes have no corresponding node in the accessibility tree (for example, because they are marked with role="presentation"). A child in the accessibility tree can thus correspond to a descendant in the DOM tree. Additionally, the use of aria-owns attribute can change the tree structure to something which is not a subtree of the DOM tree.

This definition is different from the definition of "owned element" in WAI-ARIA. Because browsers have different accessibility trees, which element owns which other elements can vary between browsers. Until there is a standard accessibility tree, testing with multiple accessibility trees may be necessary.

Owning Element

• owning element
• owning

An 'owning element' is any DOM ancestor of the element, or any element with an aria-owns attribute which references the ID of the element.

Perceivable

Presentable to users in ways they can sense. References in this document relate to WCAG 2.1 Principle 1: Content must be perceivable [[WCAG21]].

Perceivable content

A node is perceivable content if all the following are true:

• the node is palpable content; and
• the node is either visible or included in the accessibility tree; and
• if the node is an element, it does not have a semantic role of none or presentation.

Perceivable content corresponds to nodes that contain information and are perceived by some categories of users.

Assumptions for Perceivable content

This definition assumes that elements with a semantic role of none or presentation are pure decoration and that elements which are pure decoration either are not included in the accessibility tree or have a semantic role of none or presentation. Note that if this is not the case, then Success Criterion 1.3.1: Info and Relationship is likely not satisfied.

Perimeter

New

continuous line forming the boundary of a shape not including shared pixels, or the minimum bounding box of a complex shape, whichever is shortest. For example, the perimeter calculation for a rectangle is 2h+2w -4, where h is the height and w is the width and the corners are not counted twice. The perimeter of a circle is 2𝜋r.

Primary Content Element

An implementing host language's primary content element, such as the body element in HTML.

Printable characters

A printable character is a character that occupies a printing position on a display.

These characters correspond to the following Unicode categories:

• Letter: 'LC', 'Ll', 'Lm', 'Lo', 'Lt', 'Lu'
• Number: 'Nd', 'Nl', 'No'
• Mark: 'Mc', 'Me', 'Mn'
• Punctuation: 'Pc', 'Pd', 'Pe', 'Pf', 'Pi', 'Po', 'Ps'
• Symbol: 'Sc', 'Sk', 'Sm', 'So'
• Space: 'Zs'

Process

• Processes

A sequence of steps that need to be completed in order to accomplish an activity / task from end-to-end.

Programmatic Label

Element L is a programmatic label of target element T if either:

• T is a labeled control of L; or
• L is referenced by ID in the aria-labelledby attribute of T.

For more details, see examples of programmatic label.

Note: a given element may have more than one programmatic label.

Programmatically Determined Link Context

The programmatically determined context of a link (or programmatically determined link context) is the set of all elements that are included in the accessibility tree, and have one or more of the following relationships to the link:

• being an ancestor of the link in the flat tree with a semantic role of listitem; or
• being the closest ancestor of the link in the flat tree that is a p element; or
• being the closest ancestor of the link in the flat tree that has a semantic role of cell or gridcell; or
• being a header cell assigned to the closest ancestor of the link in the flat tree that has a semantic role of cell or gridcell; or
• being referenced by an aria-describedby attribute of the link.

This definition is based on the WCAG definition of programmatically determined link context.

This definition assumes that the HTML document with the link is a document using HTML according to the specification.

Programmatically Hidden

An HTML element is programmatically hidden if either it has a computed CSS property visibility whose value is not visible; or at least one of the following is true for any of its inclusive ancestors in the flat tree:

• has a hidden attribute; or
• has a computed CSS property display of none; or
• has an aria-hidden attribute set to true

Note: Contrarily to the other conditions, the visibility CSS property may be reverted by descendants.

Property

• property
• properties

Attributes that are essential to the nature of a given object, or that represent a data value associated with the object. A change of a property may significantly impact the meaning or presentation of an object. Certain properties (for example, aria-multiline) are less likely to change than states, but note that the frequency of change difference is not a rule. A few properties, such as aria-activedescendant, aria-valuenow, and aria-valuetext are expected to change often. See clarification of states versus properties.

RFC 2119

Relationship

• relationship
• relationships

A connection between two distinct things. Relationships may be of various types to indicate which object labels another, controls another, etc.

Rendered Image Resource

A rendered image resource in a web page is any resource with visible pixels that has been specified in the list of image sources of an embedded image.

Role

• role
• roles

Main indicator of type. This semantic association allows tools to present and support interaction with the object in a manner that is consistent with user expectations about other objects of that type.

Root WAI-ARIA node

The primary element containing non-metadata content. In many languages, this is the document element but in HTML, it is the <body>.

Rubric

• Rubrics

An approach to evaluation that defines a set of criteria for conformance and describes the result qualitatively.

Same key events

Two keyboard events are same key events if they have the same value for all the following attributes:

• key
• code
• location
• repeat
• isComposing

Same resource

Two or more resources can be the same resource even though the URLs for them are different. This can be due to URL parsing, server settings, redirects and DNS aliasing.

If the parsed URLs for two resources are identical, the resources are the same resource.

Depending on the server, URLs can either be case-sensitive or case-insensitive, meaning that <a href="page1.html"> and <a href="Page1.html"> lead to either the same or two different pages.

Fully parsed URLs can be different, but still lead to the same resource after making the HTTP request, due to redirects and DNS aliasing. For example, these URLs are all fully normalized: http://example.com/, http://www.example.com/, https://www.example.com/. The server can however be configured to serve the same site for http and https, and the same site for example.com and www.example.com. This is common, but not guaranteed.

Some types of redirects are also caused by user agents, e.g. ensuring that http://example.com/ and http://example.com resolve to the same resource.

On the other hand, identical relative URLs do not necessarily resolve to the same resource, even if they are in the same web page (HTML). This happen because external content can be included through iframe and URLs in or out of it will resolve relatively to different base URLs.

Scale

• Rating scale
• Rating scales
• Scales

An way of reporting results of evaluation using quantitative values.

Scrollable Elements

A scrollable element is an element with a horizontal scroll distance or a vertical scroll distance greater than 0.

• horizontal scroll distance: The difference between scrollWidth and clientWidth for elements where the computed overflow-x is auto or scroll. Undefined for other elements.
• vertical scroll distance: The difference between scrollHeight and clientHeight for elements where the computed overflow-y is auto or scroll. Undefined for other elements.

note: Elements such as iframe which can render a nested browsing context are not scrollable elements. The scrollbars on some iframe elements come from the content inside the nested browsing context.

Semantic Role

The semantic role of an element is determined by the first of these cases that applies:

1. Conflict If the element is marked as decorative, but the element is included in the accessibility tree; or would be included in the accessibility tree when it is not programmatically hidden, then its semantic role is its implicit role .
2. Explicit If the element has an explicit role, then its semantic role is its explicit role.
3. Implicit The semantic role of the element is its implicit role.

This definition can be used in expressions such as "semantic button" meaning any element with a semantic role of button.

Accessibility Support for Definition of Semantic Role for Semantic Role

• There exist popular web browsers and assistive technologies which do not correctly implement Presentational Roles Conflict Resolution. These technologies will not include in the accessibility tree elements that should be, according to Specifications. Thus, some elements that should have their semantic role fixed by case Conflict above are instead falling into case Explicit and are hidden for users of assistive technologies.
• A similar conflict exists for focusable elements with a aria-hidden="true" attribute. The WAI ARIA specification does not explain how to solve it. Some browsers give precedence to the element being focusable (and expose it in the accessibility tree) while some give precedence to the aria-hidden attribute (and hide the element).

Semantics

• semantics
• semantic
• semantically

The meaning of something as understood by a human, defined in a way that computers can process a representation of an object, such as elements and attributes, and reliably represent the object in a way that various humans will achieve a mutually consistent understanding of the object.

Semi-Automated Evaluation

Evaluation conducted using machines to guide humans to areas that need inspection.

Semi-automated evaluation involves components of automated evaluation and human evaluation.

Set of clearly labeled instruments

A set of clearly labeled instruments is a set of instruments, where each instrument is in the same web page as the test target or can be found in a clearly labeled location from that web page.

Single page Web application

• single page Web applications

New

Pages obtained from a single URI that provide navigation which changes the meaning of the Web page

Standard keyboard navigation

Standard keyboard navigation entails using one or more of the following:

• Tab key
• Shift+Tab
• Arrow keys
• Esc key
• Enter key
• Space key

Expected behavior of standard keyboard navigation keys:

• Tab key: Skipping forward between focusable elements
• Shift+Tab: Skipping backwards between focusable elements
• Arrow keys: Navigate input elements, e.g. up/down drop down, between radio buttons etc.
• Esc key: Close or cancel, e.g close a modal
• Enter key: Select or activate the element in focus (same as clicking with mouse)
• Space key: Select input elements, e.g. drop downs, radio buttons etc.

State

• state
• states

A state is a dynamic property expressing characteristics of an object that may change in response to user action or automated processes. States do not affect the essential nature of the object, but represent data associated with the object or user interaction possibilities. See clarification of states versus properties.

Sub-document

Any document created from a <frame>, <iframe> or similar mechanism. A sub-document may contain a document, an application or any widget such as a calendar pulled in from another server. In the accessibility tree there are two accessible objects for this situation—one represents the <frame>/<iframe> element in the parent document, which parents a single accessible object child representing the spawned document contents.

Success criterion

• Success criteria

Testable statements that compose the normative aspects of WCAG 2.

The closest counterpart to success criteria in WCAG 3 are outcomes.

Target Element

An element specified in a WAI-ARIA relation. For example, in <div aria-controls=”elem1”>, where “elem1” is the ID for the target element.

Taxonomy

A hierarchical definition of how the characteristics of various classes relate to each other, in which classes inherit the properties of superclasses in the hierarchy. A taxonomy can comprise part of the formal definition of an ontology.

Technique

• Techniques

Technology-specific approach to follow a method.

Test

• Tests

Mechanism to evaluate implementation of a method.

Tests can include true / false evaluation or various types of rating scales as appropriate for the guideline, outcome, or technology.

Text Inheriting its Programmatic Language from an Element

The text inheriting its programmatic language from an element E is composed of all the following texts:

• text nodes: the value of any text nodes that are visible or included in the accessibility tree and children of an element inheriting its programmatic language from E;
• accessible text: the accessible name and accessible description of any element inheriting its programmatic language from E, and included in the accessibility tree;
• page title: the value of the document title, only if E is a document in a top-level browsing context.

An element F is an element inheriting its programmatic language from an element E if at least one of the following conditions is true (recursively):

• F is E itself (an element always inherits its programmatic language from itself); or
• F does not have a non-empty lang attribute, and is the child in the flat tree of an element inheriting its programmatic language from E; or
• F is a fully active document element, has no non-empty lang attribute, and its browsing context container is an element inheriting its programmatic language from E.

Text alternative

• Text alternatives

Text that is programmatically associated with non-text content or referred to from text that is programmatically associated with non-text content. Programmatically associated text is text whose location can be programmatically determined from the non-text content.

An image of a chart is described in text in the paragraph after the chart. The short text alternative for the chart indicates that a description follows.

Text node

Type of DOM node that represents the textual content of an attribute or an element. A Text node has no child nodes.

Tooltip attribute

Any host language attribute that would result in a user agent generating a tooltip such as in response to a mouse hover in desktop user agents.

Turing test

• turing test
• turing testing

Understandable

Presentable to users in ways they can construct an appropriate meaning. References in this document relate to WCAG 2.1 Principle 3: Information and the operation of user interface must be understandable [[WCAG21]].

Unicode Braille Patterns

• unicode braille

In Unicode, braille is represented in a block called Braille Patterns (U+2800..U+28FF). The block contains all 256 possible patterns of an 8-dot braille cell; this includes the complete 6-dot cell range which is represented by U+2800..U+283F. In all braille systems, the braille pattern dots-0 (U+2800) is used to represent a space or the lack of content; it is also called a blank Braille pattern. See Braille Patterns on Wikipedia.

User Agent

• user agent
• user agents

Any software that retrieves, renders and facilitates end user interaction with Web content. This definition may differ from that used in other documents.

User interaction

A user interaction is any action that causes the user agent to fire one of the following DOM events:

• auxclick
• click
• compostionend
• compositionstart
• compositionupdate
• dblclick
• keydown
• keyup
• mousedown
• mouseenter
• mouseleave
• mousemove
• mouseout
• mouseover
• mouseup
• select
• wheel

This list comprises the User Interface event that are generated by the user agent as a result of user interaction.

User need

• User needs

The end goal a user has when starting a process through digital means.

User testing

Evaluation of content by observation of how users with specific functional needs are able to complete a process and how the content meets the relevant outcomes.

VPN

Valid IDREF

A reference to a target element in the same document that has a matching ID

Valid Language Tag

A language tag is valid if its primary language subtag exists in the language subtag registry with a Type field whose field-body value is language.

A "language tag" is here to be understood as in the first paragraph of the BCP 47 language tag syntax, i.e. a sequence of subtags separated by hyphens, where a subtag is any sequence of alphanumerical characters. Thus, this definition intentionally differs from the strict BCP 47 syntax (and ABNF grammar) as user agents and assistive technologies are more lenient in what they accept. The definition is however consistent with the behavior of the :lang() pseudo-selector as defined by Selectors Level 3. For example, de-hello would be an accepted way to indicate German in current user agents and assistive technologies, despite not being valid according to BCP 47 grammar. As a consequence of this definition, however, grandfathered tags are not correctly recognized as valid language subtags.

Subtags, notably the primary language subtag, are case insensitive. Hence comparison with the language subtag registry must be done in a case insensitive way.

View

• Views

All content visually and programmatically available without a substantive change.

Views vary based on the technology being tested. While these guidelines provide guidance on scoping a view, the tester will determine what constitutes a view, and describe it. Views will often vary by technology. Views typically include state permutations that are based on that view such as dialogs and alerts, but some states may deserve to be treated as separate views.

Visible

Content perceivable through sight.

Content is considered visible if making it fully transparent would result in a difference in the pixels rendered for any part of the document that is currently within the viewport or can be brought into the viewport via scrolling.

Content is defined in WCAG.

For more details, see examples of visible.

Visible Text Content

The visible text content of an element is a set of all visible text nodes that are descendants in the flat tree of this element

Visual Context

The visual context of a node is everything that is visually or logically located near it when the document containing it is rendered. Only visible information may be part of the visual context.

The logical distance is the distance in the structure of the document: either the tree distance within the DOM tree, or the semantic relation. For example, headings are logically near the content that follows (until the next heading of the same or higher level) even though they might be far away visually or in the DOM tree.

The visual context may include, but is not limited to, headings, text in the same sentence or paragraph.

Note: As a rule of thumb, visual context should be close enough to be displayed on the device at the same time as the element it relates to. Because device sizes vary wildly and content can further be zoomed and moved around, this is however not a strong requirement.

Note: Visual context that is located before (in reading order) the element it relates to is often more useful than visual context located after. Indeed, it is easier for users to use context that they have already read than context that is yet to be read.

Visual Contrast

The combination of foreground and background colors along with font weight and size that make text readable.

Visual Reference Words

Any word in a text node that is included in the translated version of the following lists, where the language of the translation is the programmatically determinable language of the text node. Some words can be translated in multiple ways or have plural forms. In such cases each translation or form must be included. Some words can be spelled in multiple ways (For example: sometimes the word is capitalized and sometimes it isn't). In such cases each spelling must be included.

Note: This list is not exhaustive. As soon as more visual reference words are found they can be added to this list.

Visual location:

• Above
• Below
• Beneath
• Beside
• Bottom
• Diagonal
• Down
• Left
• Near
• Nearby
• Parallel
• Right
• Top
• Under
• Underneath
• Up

Shape:

• Box
• Circle
• Circular
• Crescent
• Cross
• Diamond
• Disc
• Ellipse
• Heart
• Hexagon
• Hexagonal
• Kite
• Oval
• Parallelogram
• Pentagon
• Pentagonal
• Polygon
• Polygonal
• Rectangle
• Rectangular
• Round
• Square
• Squared
• Star
• Trapezoid
• Trapezoidal
• Triangle
• Triangular
• Wave

Size:

• Big
• Large
• Little
• Narrow
• Small
• Tiny
• Wide

Orientation:

• Angled
• Askew
• Atilt
• Crooked
• Listing
• Lopsided
• off-kilter
• Pitched
• Rotated
• Sideways
• Skewed
• Slanted
• Slanting
• Straight
• Tilt
• Tilted
• Tipped

Color

• Any single word color name in the X11 standard, omitting duplicates:

  • Almond
  • Aqua
  • Aquamarine
  • Azure
  • Beige
  • Bisque
  • Black
  • Blue
  • Brown
  • Burlywood
  • Chartreuse
  • Chiffon
  • Chocolate
  • Coral
  • Cornsilk
  • Cream
  • Crimson
  • Cyan
  • Firebrick
  • Fuchsia
  • Gold
  • Goldenrod
  • Gray
  • Green
  • Honeydew
  • Indigo
  • Ivory
  • Khaki
  • Lace
  • Lavender
  • Lemon
  • Lime
  • Linen
  • Magenta
  • Maroon
  • Mint
  • Moccasin
  • Olive
  • Orange
  • Orchid
  • Pink
  • Purple
  • Red
  • Rose
  • Salmon
  • Turquoise
  • Violet
  • White
  • Yellow

Voice User Interfaces

Sometimes called: Conversational interfaces.

Voice user interfaces (VUIs) allow the user to interact with a computer system based on audio input and/or output. Audio input can include speech, non-speech vocalizations or audio produced by AAC or other devices. Audio-based interaction may include both input from the user, and output from the system in response to the input. Examples include: Siri, Google Assistant, and Alexa.

WAI-ARIA specifications

The WAI ARIA Specifications group both the WAI ARIA W3C Recommendation and ARIA modules, namely:

• Accessible Rich Internet Applications (WAI-ARIA) 1.1
• WAI-ARIA Graphics Module 1.0
• Digital Publishing WAI-ARIA Module 1.0

Note: depending on the type of content being evaluated, part of the specifications might be irrelevant and should be ignored.

Web page

• web page(s)
• web pages

a non-embedded resource obtained from a single URI using HTTP plus any other resources that are used in the rendering or intended to be rendered together with it by a user agent

Although any "other resources" would be rendered together with the primary resource, they would not necessarily be rendered simultaneously with each other.

For the purposes of conformance with these guidelines, a resource must be "non-embedded" within the scope of conformance to be considered a Web page.

A Web resource including all embedded images and media.

A Web mail program built using Asynchronous JavaScript and XML (AJAX). The program lives entirely at http://example.com/mail, but includes an inbox, a contacts area and a calendar. Links or buttons are provided that cause the inbox, contacts, or calendar to display, but do not change the URI of the page as a whole.

A customizable portal site, where users can choose content to display from a set of different content modules.

When you enter "http://shopping.example.com/" in your browser, you enter a movie-like interactive shopping environment where you visually move around in a store dragging products off of the shelves around you and into a visual shopping cart in front of you. Clicking on a product causes it to be demonstrated with a specification sheet floating alongside. This might be a single-page Web site or just one page within a Web site.

Web page (HTML)

An HTML web page is the set of all fully active documents which share the same top-level browsing context.

Note: Nesting of browsing context mostly happens with iframe and object. Thus a web page will most of the time be a "top-level" document and all its iframe and object (recursively).

Note: Web pages as defined by WCAG are not restricted to the HTML technology but can also include, e.g., PDF or DOCX documents.

Note: Although web pages as defined here are sets of documents (and do not contain other kind of nodes), one can abusively write that any node is "in a web page" if it is a shadow-including descendant of a document that is part of that web page.

Whitespace

Whitespace are characters that have the Unicode "White_Space" property in the Unicode properties list.

This includes:

• all characters in the Unicode Separator categories, and

• the following characters in the Other, Control category:

  • Character tabulation (U+0009)
  • Line Feed (LF) (U+000A)
  • Line Tabulation (U+000B)
  • Form Feed (FF) (U+000C)
  • Carriage Return (CR) (U+000D)
  • Next Line (NEL) (U+0085)

Widget

• widget
• widgets

Discrete user interface object with which the user can interact. Widgets range from simple objects that have one value or operation (e.g., check boxes and menu items), to complex objects that contain many managed sub-objects (e.g., trees and grids).

abbreviation

• abbreviations

shortened form of a word, phrase, or name where the abbreviation has not become part of the language

This includes initialisms and acronyms where:

1. initialisms are shortened forms of a name or phrase made from the initial letters of words or syllables contained in that name or phrase

   Not defined in all languages.

   SNCF is a French initialism that contains the initial letters of the Société Nationale des Chemins de Fer, the French national railroad.

   ESP is an initialism for extrasensory perception.

2. acronyms are abbreviated forms made from the initial letters or parts of other words (in a name or phrase) which may be pronounced as a word

   NOAA is an acronym made from the initial letters of the National Oceanic and Atmospheric Administration in the United States.

Some companies have adopted what used to be an initialism as their company name. In these cases, the new name of the company is the letters (for example, Ecma) and the word is no longer considered an abbreviation.

accessibility information (WCAG)

accessibility problems

• authoring tool user interface accessibility problems: Aspects of an authoring tool user interface that does not meet a success criterion in Part A of ATAG 2.0.
• web content accessibility problems (WCAG): Aspects of web content that does not meet a WCAG 2.0 success criterion (Level A, AA or AAA).

accessibility supported

• accessibility-supported
• accessibility support

supported by users' assistive technologies as well as the accessibility features in browsers and other user agents

To qualify as an accessibility-supported use of a Web content technology (or feature of a technology), both 1 and 2 must be satisfied for a Web content technology (or feature):

1. The way that the Web content technology is used must be supported by users' assistive technology (AT). This means that the way that the technology is used has been tested for interoperability with users' assistive technology in the human language(s) of the content,

   AND

2. The Web content technology must have accessibility-supported user agents that are available to users. This means that at least one of the following four statements is true:

   1. The technology is supported natively in widely-distributed user agents that are also accessibility supported (such as HTML and CSS);

      OR

   2. The technology is supported in a widely-distributed plug-in that is also accessibility supported;

      OR

   3. The content is available in a closed environment, such as a university or corporate network, where the user agent required by the technology and used by the organization is also accessibility supported;

      OR

   4. The user agent(s) that support the technology are accessibility supported and are available for download or purchase in a way that:

      • does not cost a person with a disability any more than a person without a disability and
      • is as easy to find and obtain for a person with a disability as it is for a person without disabilities.

The Accessibility Guidelines Working Group and the W3C do not specify which or how much support by assistive technologies there must be for a particular use of a Web technology in order for it to be classified as accessibility supported. (See Level of Assistive Technology Support Needed for "Accessibility Support".)

Web technologies can be used in ways that are not accessibility supported as long as they are not relied upon and the page as a whole meets the conformance requirements, including Conformance Criterion 4 and Conformance Criterion 5, are met.

When a Web Technology is used in a way that is "accessibility supported," it does not imply that the entire technology or all uses of the technology are supported. Most technologies, including HTML, lack support for at least one feature or use. Pages conform to WCAG only if the uses of the technology that are accessibility supported can be relied upon to meet WCAG requirements.

When citing Web content technologies that have multiple versions, the version(s) supported should be specified.

One way for authors to locate uses of a technology that are accessibility supported would be to consult compilations of uses that are documented to be accessibility supported. (See Understanding Accessibility-Supported Web Technology Uses.) Authors, companies, technology vendors, or others may document accessibility-supported ways of using Web content technologies. However, all ways of using technologies in the documentation would need to meet the definition of accessibility-supported Web content technologies above.

accessible content support features

activate

alternative content

• text alternative for non-text content: Text that is programmatically associated with non-text content or referred to from text that is programmatically associated with non-text content. For example, an image of a chart might have two text alternatives: a short text alternative and a described-by relationship to a nearby paragraph that more fully describes the content of the chart.
• alternative for time-based media: Web content that serves the same function or purpose as one or more tracks in a time-based media presentation. This includes alternatives for audio such as captions and sign language interpretation, and alternatives for video such as audio descriptions and extended audio descriptions. Another form of time-based media alternative is a correctly sequenced text description of time-based visual and auditory information that also is capable of achieving the outcomes of any interactivity in the time-based presentation.
• text alternatives for text content: Text that is programmatically associated with certain types of text content to provide expanded information. For example, an abbreviation (or acronym) can provide an expansion of the shortened word or initialized words (<abbr title="User Agent Accessibility Guidelines">UAAG</abbr>).

• media alternative for text: Media that presents no more information than is already presented in text (directly or via text alternatives). A media alternative for text is provided for people who benefit from alternate representations of text. Media alternatives for text can be audio-only, video-only (including sign-language video), or audio-video.

alternative content

• text alternatives for non-text content: Text that is programmatically associated with non-text content or referred to from text that is programmatically associated with non-text content. For example, an image of a chart might have two text alternatives: a description in the paragraph after the chart and a short text alternative for the chart indicating in words that a description follows.
• alternatives for time-based media: Web content that serves the same function or purpose as one or more tracks in a time-based media presentation. This includes: captions, audio descriptions, extended audio descriptions, sign language interpretation as well as correctly sequenced text descriptions of time-based visual and auditory information that also is capable of achieving the outcomes of any interactivity in the time-based presentation.
• media alternative for text: Media that presents no more information than is already presented in text (directly or via text alternatives). A media alternative for text is provided for people who benefit from alternate representations of text. Media alternatives for text may be audio-only, video-only (including sign-language video), or audio-video.

• programmatically associated alternative content: Alternative content whose location and purpose can be programmatically determined from the original content for which it is serving as an alternative. For example, a paragraph might serve as a text alternative for an image, but it is only programmatically associated if this relationship is properly encoded (e.g. by "aria-labeledby").

  Note: ATAG 2.0 typically refers to programmatically associated alternative content.

alternative for time-based media

document including correctly sequenced text descriptions of time-based visual and auditory information and providing a means for achieving the outcomes of any time-based interaction

A screenplay used to create the synchronized media content would meet this definition only if it was corrected to accurately represent the final synchronized media after editing.

alternative text

ambiguous to users in general

the purpose cannot be determined from the link and all information of the Web page presented to the user simultaneously with the link (i.e., readers without disabilities would not know what a link would do until they activated it)

The word guava in the following sentence "One of the notable exports is guava" is a link. The link could lead to a definition of guava, a chart listing the quantity of guava exported or a photograph of people harvesting guava. Until the link is activated, all readers are unsure and the person with a disability is not at any disadvantage.

animation

application programming interface (API)

assistive technology

• assistive technology
• assistive technologies

assistive technology

1. Relies on services (such as retrieving web resources and parsing markup) provided by one or more host user agents.
2. Communicates data and messages with host user agents by monitoring and using APIs.
3. Provides services beyond those offered by the host user agents to meet the requirements of users with disabilities. Additional services include alternative renderings (e.g. as synthesized speech or magnified content), alternative input methods (e.g. voice), additional navigation or orientation mechanisms, and content transformations (e.g. to make tables more accessible).

• Screen magnifiers, which are used by people with visual disabilities to enlarge and change colors on the screen to improve the visual readability of rendered text and images.
• Screen readers, which are used by people who are blind or have reading disabilities to read textual information through synthesized speech or braille displays.
• Voice recognition software, which is used by some people who have physical disabilities to simulate the keyboard and mouse.
• Alternative keyboards, which are used by some people with physical disabilities to simulate the keyboard and mouse.
• Alternative pointing devices, which are used by some people with physical disabilities to simulate mouse pointing and button activations.

assistive technology

• screen magnifiers, and other visual reading assistants, which are used by people with visual, perceptual, and physical print disabilities to change text font, size, spacing, color, synchronization with speech, etc. in order improve the visual readability of rendered text and images;
• screen readers, which are used by people who are blind to read textual information through synthesized speech or Braille;
• text-to-speech software, which is used by some people with cognitive, language, and learning disabilities to convert text into synthetic speech;
• speech recognition software, which are used by some people who have some physical disabilities;
• alternative keyboards, which are used by some people with physical disabilities to simulate the keyboard (including alternate keyboards that use head pointers, single switches, sip/puff, and other special input devices);
• alternative pointing devices, which are used by some people with physical disabilities to simulate mouse pointing and button activations.

assistive technology (as used in this document)

• assistive technologies

hardware and/or software that acts as a user agent, or along with a mainstream user agent, to provide functionality to meet the requirements of users with disabilities that go beyond those offered by mainstream user agents

functionality provided by assistive technology includes alternative presentations (e.g., as synthesized speech or magnified content), alternative input methods (e.g., voice), additional navigation or orientation mechanisms, and content transformations (e.g., to make tables more accessible).

Assistive technologies often communicate data and messages with mainstream user agents by using and monitoring APIs.

The distinction between mainstream user agents and assistive technologies is not absolute. Many mainstream user agents provide some features to assist individuals with disabilities. The basic difference is that mainstream user agents target broad and diverse audiences that usually include people with and without disabilities. Assistive technologies target narrowly defined populations of users with specific disabilities. The assistance provided by an assistive technology is more specific and appropriate to the needs of its target users. The mainstream user agent may provide important functionality to assistive technologies like retrieving Web content from program objects or parsing markup into identifiable bundles.

Assistive technologies that are important in the context of this document include the following:

• screen magnifiers, and other visual reading assistants, which are used by people with visual, perceptual and physical print disabilities to change text font, size, spacing, color, synchronization with speech, etc. in order to improve the visual readability of rendered text and images;
• screen readers, which are used by people who are blind to read textual information through synthesized speech or braille;
• text-to-speech software, which is used by some people with cognitive, language, and learning disabilities to convert text into synthetic speech;
• speech recognition software, which may be used by people who have some physical disabilities;
• alternative keyboards, which are used by people with certain physical disabilities to simulate the keyboard (including alternate keyboards that use head pointers, single switches, sip/puff and other special input devices.);
• alternative pointing devices, which are used by people with certain physical disabilities to simulate mouse pointing and button activations.

audio

the technology of sound reproduction

Audio can be created synthetically (including speech synthesis), recorded from real world sounds, or both.

audio

audio

audio description

• audio descriptions

narration added to the soundtrack to describe important visual details that cannot be understood from the main soundtrack alone

Audio description of video provides information about actions, characters, scene changes, on-screen text, and other visual content.

In standard audio description, narration is added during existing pauses in dialogue. (See also extended audio description.)

Where all of the video information is already provided in existing audio, no additional audio description is necessary.

Also called "video description" and "descriptive narration."

audio description

• extended audio description: An audio description in which the video is sometimes paused so that there is time to add additional description.

audio track

audio-only

a time-based presentation that contains only audio (no video and no interaction)

author

author actions preventing generation of accessible web content

author permission

authoring action

• reversible authoring action: An authoring action that can be immediately and completely undone by the authoring tool upon a cancel request by an author. Examples of cancel requests include: "cancel", "undo", "redo" (when it used to reverse "undo"), "revert", and "roll-back"

  Note: It is acceptable for an authoring tool to collect a series of text entry actions (e.g. typed words, a series of backspaces) into a single reversible authoring action.

authoring outcome

authoring practice

• accessible authoring practices (WCAG): An authoring practice in which the authoring outcome conforms to WCAG 2.0 at Level A, AA, or AAA. Some accessible authoring practices require accessibility information (WCAG).

authoring session

• end of an authoring session: The point at which the author has no further opportunity to make authoring actions without starting another session. The end of an authoring session may be determined by authors (e.g. closing a document, publishing) or by the authoring tool (e.g. when the authoring tool transfers editing permission to another author on a collaborative system).

  Note: The end of the authoring session is distinct from publishing. Automatic content generation may continue after the end of both the authoring session and initial publishing (e.g. content management system updates).

authoring tool

• web page authoring tools (e.g. WYSIWYG HTML editors)
• software for directly editing source code
• software for converting to web content technologies (e.g. "Save as HTML" features in office document applications)
• integrated development environments (e.g. for web application development)
• software that generates web content on the basis of templates, scripts, command-line input or "wizard"-type processes
• software for rapidly updating portions of web pages (e.g. blogging, wikis, online forums)
• software for generating/managing entire websites (e.g. content management systems, courseware tools, content aggregators)
• email clients that send messages using web content technologies
• multimedia authoring tools
• software for creating mobile web applications

• customizable personal portals: ATAG 2.0 does not apply because the web content being edited is only available to the owner of the portal
• e-commerce order forms: ATAG 2.0 does not apply because the purpose of an e-commerce order form is to order a product, not communicate with other people via web content, even if the data collected by the form actually does result in web content (e.g. online tracking pages)

• stand-alone accessibility checkers: ATAG 2.0 does not apply because a stand-alone accessibility checker with no automated or semi-automated repair functionality does not actually modify web content. An accessibility checker with repair functionality or that is considered as part of a larger authoring process would be considered an authoring tool.

authoring tool user interface

• authoring tool user interface (non-web-based): Any parts of an authoring tool user interface that are not implemented as web content and instead run directly on a platform that is not a user agent (e.g. Windows, Mac OS, Java Virtual Machine, iOS, Android).
• authoring tool user interface (web-based): Any parts of an authoring tool user interface that are implemented using web content technologies and are accessed by authors via a user agent.

• accessible authoring tool user interfaces: Authoring tool user interfaces that meet the success criteria of a level in Part A of ATAG 2.0.

authors

available printing devices

blinking

switch back and forth between two visual states in a way that is meant to draw attention

See also flash. It is possible for something to be large enough and blink brightly enough at the right frequency to be also classified as a flash.

blocks of text

more than one sentence of text

captions

synchronized visual and/or text alternative for both speech and non-speech audio information needed to understand the media content

Captions are similar to dialogue-only subtitles except captions convey not only the content of spoken dialogue, but also equivalents for non-dialogue audio information needed to understand the program content, including sound effects, music, laughter, speaker identification and location.

Closed Captions are equivalents that can be turned on and off with some players.

Open Captions are any captions that cannot be turned off. For example, if the captions are visual equivalent images of text embedded in video.

Captions should not obscure or obstruct relevant information in the video.

In some countries, captions are called subtitles.

Audio descriptions can be, but do not need to be, captioned since they are descriptions of information that is already presented visually.

captions

• open captions: Captions that are always rendered with a visual track; they cannot be turned off.
• closed captions: Captions that can be turned on and off. The captions requirements of UAAG 2.0 assume that the user agent can recognize the captions as such.

changes of context

• change of context

major changes in the content of the Web page that, if made without user awareness, can disorient users who are not able to view the entire page simultaneously

Changes in context include changes of:

1. user agent;
2. viewport;
3. focus;
4. content that changes the meaning of the Web page

A change of content is not always a change of context. Changes in content, such as an expanding outline, dynamic menu, or a tab control do not necessarily change the context, unless they also change one of the above (e.g., focus).

Opening a new window, moving focus to a different component, going to a new page (including anything that would look to a user as if they had moved to a new page) or significantly re-arranging the content of a page are examples of changes of context.

checking, accessibility

• manual checking: Checking in which the tests are carried out by authors. This includes the case where authors are aided by instructions or guidance provided by the authoring tool, but where authors must carry out the actual test procedure.
• semi-automated checking: Checking in which the tests are partially carried out by the authoring tool, but where authors' input or judgment is still required to decide or help decide the outcome of the tests.
• automated checking: Checking in which the tests are carried out automatically by the authoring tool without any intervention by authors.

commands

• direct commands: Commands that apply to a specified item (e.g. button) or action (e.g. save function), regardless of the current focus location. Also see keyboard command
  • direct navigation commands: Commands that move focus to a specified item.
  • direct activation commands: Commands that activate the specified item (and can also move focus to it) or action.
• sequential navigation commands (sometimes called "logical navigation commands" or "linear navigation commands"): Commands that move focus forwards and backwards through a list of items. The element list being navigated can be the list of all elements or just a subset (e.g. the list of headers, the list of links).
• spatial commands (sometimes called "directional commands"): Commands that require the user to be aware of the spatial arrangement of items on the screen:
  • spatial navigation commands: Commands that move from one item to another based on direction on the screen.
  • spatial manipulation commands: Commands that resize or reposition an item on the screen.
• structural navigation commands: Commands that move forwards, backwards, up and down a hierarchy.

conformance

• conform

satisfying all the requirements of a given standard, guideline or specification

conforming alternate version

• conforming alternate versions

version that

1. conforms at the designated level, and
2. provides all of the same information and functionality in the same human language, and
3. is as up to date as the non-conforming content, and

4. for which at least one of the following is true:

   1. the conforming version can be reached from the non-conforming page via an accessibility-supported mechanism, or
   2. the non-conforming version can only be reached from the conforming version, or
   3. the non-conforming version can only be reached from a conforming page that also provides a mechanism to reach the conforming version

In this definition, "can only be reached" means that there is some mechanism, such as a conditional redirect, that prevents a user from "reaching" (loading) the non-conforming page unless the user had just come from the conforming version.

The alternate version does not need to be matched page for page with the original (e.g., the conforming alternate version may consist of multiple pages).

If multiple language versions are available, then conforming alternate versions are required for each language offered.

Alternate versions may be provided to accommodate different technology environments or user groups. Each version should be as conformant as possible. One version would need to be fully conformant in order to meet conformance requirement 1.

The conforming alternative version does not need to reside within the scope of conformance, or even on the same Web site, as long as it is as freely available as the non-conforming version.

Alternate versions should not be confused with supplementary content, which support the original page and enhance comprehension.

Setting user preferences within the content to produce a conforming version is an acceptable mechanism for reaching another version as long as the method used to set the preferences is accessibility supported.

See Understanding Conforming Alternate Versions

content (Web content)

information and sensory experience to be communicated to the user by means of a user agent, including code or markup that defines the content's structure, presentation, and interactions

content (structured)

content (web content)

content (web content)

• accessible content (WCAG): Content that would conform to WCAG 2.0, at either Level A, AA, or AAA, assuming that any web content technologies relied upon to satisfy the WCAG 2.0 success criteria are accessibility supported.
  • Note 1: If accessibility support for the relied upon technologies is lacking, then the content will not conform to WCAG 2.0 and one or more groups of end users with disabilities will likely experience difficulty accessing the content.
  • Note 2: Conformance to WCAG 2.0, even at the highest level (i.e. Level AAA), still may not make content "accessible to individuals with all types, degrees, or combinations of disability".
• content being edited: The web content that an author can modify during an authoring session. The content being edited may be a complete piece of content (e.g. image, style sheet) or only part of a larger piece of content (e.g. a status update). The content being edited only includes content in web content technologies that the authoring tool supports (e.g. a WYSIWYG HTML editor allows editing of the HTML content of a web page editable, but not the images).

content generation (content authoring, content editing)

• author generated content: Web content for which authors are fully responsible. The author may only be responsible down to a particular level (e.g. when asked to type a text label, the author is responsible for the text, but not for how the label is marked up; when typing markup in a source editing-view, the author is not responsible for the fact that UNICODE is used to encode the text ).
• automatically-generated content: Web content for which developer-programmed functionality is fully responsible (e.g. what markup to output when an author requests to start a new document, automatically correcting markup errors).
• third-party content generation: Web content for which a third-party author is responsible (e.g. community shared templates).

content properties

content rendering

• conventional renderings (or "WYSIWYG"): When content is rendered in a way that is similar to the default rendering a user agent would create from the same content. While "WYSIWYG", standing for "What-you-see-is-what-you-get" is the common term, differences between user agents and end user settings mean that in reality there is no single typical end user experience; or
• unconventional renderings: When content is rendered differently than it would be in a typical user agent (e.g. rendering an audio file as a graphical waveform); or
• partial renderings: When some aspects of the content are rendered, played, or executed, but not others (e.g. a frame-by-frame video editor renders the graphical, but not the timing aspects, of a video).

content transformations

• Optimizing Content Transformations: Transformations in which the content technology is not changed and the structural features of the content technology that are employed also stay the same. Changes would not be expected to result in information loss (e.g. removing whitespace, replacing in-line styles with an external style sheet).
• Restructuring Content Transformations: Transformations in which the content technology stays the same, but the structural features of the technology used to markup the content are changed (e.g. linearizing tables, splitting a document into pages.
• Recoding Content Transformations: Transformations in which the content technology used to encode the content is changed (e.g. HTML to XHTML, a word processing format to HTML).

context-sensitive help

help text that provides information related to the function currently being performed

Clear labels can act as context-sensitive help.

continuous authentication

continuous scale

contrast ratio

(L1 + 0.05) / (L2 + 0.05), where

• L1 is the relative luminance of the lighter of the colors, and
• L2 is the relative luminance of the darker of the colors.

Contrast ratios can range from 1 to 21 (commonly written 1:1 to 21:1).

Because authors do not have control over user settings as to how text is rendered (for example font smoothing or anti-aliasing), the contrast ratio for text can be evaluated with anti-aliasing turned off.

For the purpose of Success Criteria 1.4.3 and 1.4.6, contrast is measured with respect to the specified background over which the text is rendered in normal usage. If no background color is specified, then white is assumed.

Background color is the specified color of content over which the text is to be rendered in normal usage. It is a failure if no background color is specified when the text color is specified, because the user's default background color is unknown and cannot be evaluated for sufficient contrast. For the same reason, it is a failure if no text color is specified when a background color is specified.

When there is a border around the letter, the border can add contrast and would be used in calculating the contrast between the letter and its background. A narrow border around the letter would be used as the letter. A wide border around the letter that fills in the inner details of the letters acts as a halo and would be considered background.

WCAG conformance should be evaluated for color pairs specified in the content that an author would expect to appear adjacent in typical presentation. Authors need not consider unusual presentations, such as color changes made by the user agent, except where caused by authors' code.

control settings

correct reading sequence

any sequence where words and paragraphs are presented in an order that does not change the meaning of the content

default

developer

direct accessibility features

directly

disabled element

display settings

• audio display settings: the characteristics of audio output of music, sounds, and speech. Examples include volume, speech voices, voice speed, and voice emphasis.
• visual display settings: the characteristics of the on-screen rendering of text and graphics. Examples include fonts, sizes, colors, spacing, positioning, and contrast.
• tactile display settings: the characteristics of haptic output. Examples include the magnitude of the haptic forces and the types of vibration.

document character set

document object

document object, Document Object Model (DOM)

documentation

documentation

down-event

platform event that occurs when the trigger stimulus of a pointer is depressed

The down-event may have different names on different platforms, such as "touchstart" or "mousedown".

dragging movement

• dragging movements

New

an operation where the pointer engages with an element on the down event and the element (or a representation of its position) follows the pointer

The element could be, for example, a list item, a text element, or an image.

element

• enabled element: An element with associated behaviors that can be activated through the user interface or through an API. The set of elements that a user agent enables is generally derived from, but is not limited to, the set of elements defined by implemented markup languages.
• disabled element: A potentially enabled element that is not currently available for activation (e.g. a "grayed out" menu item).
• element type : A category of elements (such as images, videos, sounds, first level headings, lists, or list items).

element

emergency

a sudden, unexpected situation or occurrence that requires immediate action to preserve health, safety, or property

enabled element

end user

essential

if removed, would fundamentally change the information or functionality of the content, and information and functionality cannot be achieved in another way that would conform

events and scripting, event handler, event type

explicit user request

extended audio description

audio description that is added to an audiovisual presentation by pausing the video so that there is time to add additional description

This technique is only used when the sense of the video would be lost without the additional audio description and the pauses between dialogue/narration are too short.

extended audio description

flash

• flashes

a pair of opposing changes in relative luminance that can cause seizures in some people if it is large enough and in the right frequency range

See general flash and red flash thresholds for information about types of flash that are not allowed.

See also blinking.

focus

• Focus

New

the point where the user’s input interacts with the web page. For example, tabbing through a page with a keyboard moves the focus. Clicking or tapping on the page would move the focus for mouse and touchscreen usage. Different inputs can be used by a user, but at any one time there would be one point of focus for the user with the last input used.

focus cursor

• keyboard focus cursor: Indicator showing the enabled element with current input focus where focus has been moved by the keyboard (e.g. the dotted line around a button).
• text cursor: Indicator showing where keyboard input will occur in text (e.g. the flashing vertical bar in a text field, also called a caret).
• pointer: Indicator showing where pointing device input will occur. The indicator can be moved with a pointing device or emulator such as a mouse, pen tablet, keyboard-based mouse emulator, speech-based mouse commands, or 3-D wand. A pointing device click typically moves the input focus to the pointer location. The indicator can change to reflect different states. When touchscreens are used, the "pointing device" is a combination of the touchscreen and the user's finger or stylus. On most touchscreen systems there is no pointer (on-screen visual indication).

focus indicator

New

the pixels that are changed to visually indicate when a user interface component is in a focused state.

focus, input focus

• keyboard focus: The screen location where keyboard input will occur if a viewport is active.
• pointing device focus: The screen location where pointer input will occur if a viewport is active. There can be multiple pointing device foci for example when using a screen sharing utility there is typically one for the user's physical mouse and one for the remote mouse.

focusable element

functionality

processes and outcomes achievable through user action

general flash and red flash thresholds

a flash or rapidly changing image sequence is below the threshold (i.e., content passes) if any of the following are true:

1. there are no more than three general flashes and / or no more than three red flashes within any one-second period; or
2. the combined area of flashes occurring concurrently occupies no more than a total of .006 steradians within any 10 degree visual field on the screen (25% of any 10 degree visual field on the screen) at typical viewing distance

where:

• A general flash is defined as a pair of opposing changes in relative luminance of 10% or more of the maximum relative luminance where the relative luminance of the darker image is below 0.80; and where "a pair of opposing changes" is an increase followed by a decrease, or a decrease followed by an increase, and
• A red flash is defined as any pair of opposing transitions involving a saturated red

Exception: Flashing that is a fine, balanced, pattern such as white noise or an alternating checkerboard pattern with "squares" smaller than 0.1 degree (of visual field at typical viewing distance) on a side does not violate the thresholds.

For general software or Web content, using a 341 x 256 pixel rectangle anywhere on the displayed screen area when the content is viewed at 1024 x 768 pixels will provide a good estimate of a 10 degree visual field for standard screen sizes and viewing distances (e.g., 15-17 inch screen at 22-26 inches). (Higher resolutions displays showing the same rendering of the content yield smaller and safer images so it is lower resolutions that are used to define the thresholds.)

A transition is the change in relative luminance (or relative luminance/color for red flashing) between adjacent peaks and valleys in a plot of relative luminance (or relative luminance/color for red flashing) measurement against time. A flash consists of two opposing transitions.

The current working definition in the field for "pair of opposing transitions involving a saturated red" is where, for either or both states involved in each transition, R/(R+ G + B) >= 0.8, and the change in the value of (R-G-B)x320 is > 20 (negative values of (R-G-B)x320 are set to zero) for both transitions. R, G, B values range from 0-1 as specified in “relative luminance” definition. [[HARDING-BINNIE]]

Tools are available that will carry out analysis from video screen capture. However, no tool is necessary to evaluate for this condition if flashing is less than or equal to 3 flashes in any one second. Content automatically passes (see #1 and #2 above).

globally, global configuration

graphical

heuristic

• heuristic
• heuristics

highlight, highlighted, highlighting

honeypot

• honeypot
• honeypots

human language

• human language(s)

language that is spoken, written or signed (through visual or tactile means) to communicate with humans

See also sign language.

human language

idiom

• idioms

phrase whose meaning cannot be deduced from the meaning of the individual words and the specific words cannot be changed without losing the meaning

idioms cannot be translated directly, word for word, without losing their (cultural or language-dependent) meaning.

In English, "spilling the beans" means "revealing a secret." However, "knocking over the beans" or "spilling the vegetables" does not mean the same thing.

In Japanese, the phrase "さじを投げる" literally translates into "he throws a spoon," but it means that there is nothing he can do and finally he gives up.

In Dutch, "Hij ging met de kippen op stok" literally translates into "He went to roost with the chickens," but it means that he went to bed early.

image

image of text

• images of text

text that has been rendered in a non-text form (e.g., an image) in order to achieve a particular visual effect

This does not include text that is part of a picture that contains significant other visual content.

A person's name on a nametag in a photograph.

informative

for information purposes and not required for conformance

Content required for conformance is referred to as "normative."

informative

informative (non-normative)

input error

information provided by the user that is not accepted

jargon

words used in a particular way by people in a particular field

The word StickyKeys is jargon from the field of assistive technology/accessibility.

keyboard

keyboard command (keyboard binding, keyboard shortcuts, accesskey, access key, accelerator keys, direct keyboard command)

keyboard interface

interface used by software to obtain keystroke input

Operation of the application (or parts of the application) through a keyboard-operated mouse emulator, such as MouseKeys, does not qualify as operation through a keyboard interface because operation of the program is through its pointing device interface, not through its keyboard interface.

keyboard interface

keyboard interface

keyboard shortcut

• keyboard shortcuts

alternative means of triggering an action by the pressing of one or more keys

keyboard trap

label

• labels

text or other component with a text alternative that is presented to a user to identify a component within Web content

A label is presented to all users whereas the name may be hidden and only exposed by assistive technology. In many (but not all) cases the name and the label are the same.

The term label is not limited to the label element in HTML.

label

large scale (text)

• large-scale

with at least 18 point or 14 point bold or font size that would yield equivalent size for Chinese, Japanese and Korean (CJK) fonts

Fonts with extraordinarily thin strokes or unusual features and characteristics that reduce the familiarity of their letter forms are harder to read, especially at lower contrast levels.

Font size is the size when the content is delivered. It does not include resizing that may be done by a user.

The actual size of the character that a user sees is dependent both on the author-defined size and the user's display or user-agent settings. For many mainstream body text fonts, 14 and 18 point is roughly equivalent to 1.2 and 1.5 em or to 120% or 150% of the default size for body text (assuming that the body font is 100%), but authors would need to check this for the particular fonts in use. When fonts are defined in relative units, the actual point size is calculated by the user agent for display. The point size should be obtained from the user agent, or calculated based on font metrics as the user agent does, when evaluating this success criterion. Users who have low vision would be responsible for choosing appropriate settings.

When using text without specifying the font size, the smallest font size used on major browsers for unspecified text would be a reasonable size to assume for the font. If a level 1 heading is rendered in 14pt bold or higher on major browsers, then it would be reasonable to assume it is large text. Relative scaling can be calculated from the default sizes in a similar fashion.

The 18 and 14 point sizes for roman texts are taken from the minimum size for large print (14pt) and the larger standard font size (18pt). For other fonts such as CJK languages, the "equivalent" sizes would be the minimum large print size used for those languages and the next larger standard large print size.

legal commitments

transactions where the person incurs a legally binding obligation or benefit

A marriage license, a stock trade (financial and legal), a will, a loan, adoption, signing up for the army, a contract of any type, etc.

link purpose

• purpose of each link

nature of the result obtained by activating a hyperlink

live

information captured from a real-world event and transmitted to the receiver with no more than a broadcast delay

A broadcast delay is a short (usually automated) delay, for example used in order to give the broadcaster time to cue or censor the audio (or video) feed, but not sufficient to allow significant editing.

If information is completely computer generated, it is not live.

live

lower secondary education level

the two or three year period of education that begins after completion of six years of school and ends nine years after the beginning of primary education

This definition is based on the International Standard Classification of Education [[UNESCO]].

markup language

• markup of some content is the set of annotations that appear in the content.

mechanism

process or technique for achieving a result

The mechanism may be explicitly provided in the content, or may be relied upon to be provided by either the platform or by user agents, including assistive technologies.

The mechanism needs to meet all success criteria for the conformance level claimed.

media alternative for text

media that presents no more information than is already presented in text (directly or via text alternatives)

A media alternative for text is provided for those who benefit from alternate representations of text. Media alternatives for text may be audio-only, video-only (including sign-language video), or audio-video.

minimum bounding box

New

the smallest enclosing box within which all the points of a shape lie. Where a component consists of disconnected parts, such as a link that wraps onto multiple lines, each part is considered to have its own bounding box.

motion animation

addition of steps between conditions to create the illusion of movement or to give a sense of a smooth transition

For example, an element which moves into place or changes size while appearing is considered to be animated. An element which appears instantly without transitioning is not using animation. Motion animation does not include changes of color, blurring, or opacity which do not change the perceived size, shape, or position of the element.

name

text by which software can identify a component within Web content to the user

The name may be hidden and only exposed by assistive technology, whereas a label is presented to all users. In many (but not all) cases, the label and the name are the same.

This is unrelated to the name attribute in HTML.

name

navigated sequentially

navigated in the order defined for advancing focus (from one element to the next) using a keyboard interface

non-interactive

non-text content

any content that is not a sequence of characters that can be programmatically determined or where the sequence is not expressing something in human language

This includes ASCII Art (which is a pattern of characters), emoticons, leetspeak (which uses character substitution), and images representing text

non-text content

non-text content (non-text element, non-text equivalent)

normative

required for conformance

One may conform in a variety of well-defined ways to this document.

Content identified as "informative" or "non-normative" is never required for conformance.

normative

normative, informative (non-normative)

notify

obscure

on a full-screen window

on the most common sized desktop/laptop display with the viewport maximized

Since people generally keep their computers for several years, it is best not to rely on the latest desktop/laptop display resolutions but to consider the common desktop/laptop display resolutions over the course of several years when making this evaluation.

operating environment

operating system (OS)

option

• default option: A setting or value for an option that is assigned automatically by the authoring tool and remains in effect unless canceled or changed by the author.

override

page break locators

• pagebreak locators

New

programmatically determinable destination markers that are arranged in a meaningful sequence to determine the location of a page in relation to others in the set.

Examples would be:

• A digital version of an ebook that has a print version, it includes the page break locators to align with the print edition.
• A digital book is published with no print equivalent and page break locators are inserted which supports direct navigation across platforms and form factors.

paused

• pause

stopped by user request and not resumed until requested by user

placeholder

platform

platform

platform accessibility service

platform accessibility service

plug-in

plug-in

point of regard

pointer

pointer input

• pointer inputs

input device that can target a specific coordinate (or set of coordinates) on a screen, such as a mouse, pen, or touch contact

See also Pointer Events pointer definition [[!pointerevents]].

pre-authored content

• accessible pre-authored content (WCAG): Pre-authored content that is either already accessible web content (WCAG) or would be accessible, if it was appropriately inserted into an empty document.

  Note: If extensive author input is required to make use of pre-authored content, then the content may in fact be a template.

pre-authored content selection mechanism

prerecorded

information that is not live

presentation

rendering of the content in a form to be perceived by users

presentation

primary education level

• primary education

six year time period that begins between the ages of five and seven, possibly without any previous education

This definition is based on the International Standard Classification of Education [[UNESCO]].

process

• processes

series of user actions where each action is required in order to complete an activity

Successful use of a series of Web pages on a shopping site requires users to view alternative products, prices and offers, select products, submit an order, provide shipping information and provide payment information.

An account registration page requires successful completion of a Turing test before the registration form can be accessed.

profile

programmatically available

programmatically determined (programmatically determinable)

• programmatically determinable

determined by software from author-supplied data provided in a way that different user agents, including assistive technologies, can extract and present this information to users in different modalities

Determined in a markup language from elements and attributes that are accessed directly by commonly available assistive technology.

Determined from technology-specific data structures in a non-markup language and exposed to assistive technology via an accessibility API that is supported by commonly available assistive technology.

programmatically determined (programmatically determinable)

• Processing content: Whether the authoring tool is able to extract information from the web content (e.g. to extract the language of content from the markup).

• Communication between the authoring tool and assistive technology: For non-web-based user interfaces, this means making use of platform accessibility services, APIs, and, in some cases, document object models. For web-based user interfaces, this means ensuring that the user agent can pass on the information (e.g. through the use of WAI-ARIA).

programmatically determined link context

additional information that can be programmatically determined from relationships with a link, combined with the link text, and presented to users in different modalities

In HTML, information that is programmatically determinable from a link in English includes text that is in the same paragraph, list, or table cell as the link or in a table header cell that is associated with the table cell that contains the link.

Since screen readers interpret punctuation, they can also provide the context from the current sentence, when the focus is on a link in that sentence.

programmatically set

set by software using methods that are supported by user agents, including assistive technologies

prominence

• at least as prominent: For ATAG 2.0, a user interface component A is considered to be "at least as prominent" as another component B when, from a default state, component A becomes displayed (and enabled) with the same number or less "opening" actions than are required for component B to become displayed (and enabled).

  Note 1: When a container is open, all of the enabled components in the container (e.g. items in a list, items in a menu, buttons in a toolbar, all components in a dialog box) are considered to be displayed (and therefore are at least as prominent as each other), even if the container must be scrolled for them to become visible. This takes into account that different screen sizes and author settings will affect which components are visible at a given time.

  Note 2: "Opening actions" are actions made by authors on components within the user interface that result in new components becoming displayed or enabled. For example: (a) keyboard shortcut to a top-level menu item to display a sub-menu, (b) keyboard selection on a button to display a dialog box, (c) mouse click on a checkbox to enable previously disabled sub-items, etc. Actions that do not cause new components to become actionable (e.g. moving focus, scrolling a list), are not counted as "opening actions".

  Note 3: Keyboard shortcuts to components in closed containers are not counted as "opening actions" because the components have no prominence when they are not displayed. The same is true when authors must use "search" to reveal components in closed containers.

  Note 4: The "default state" is the state of the authoring tool at the beginning of an authoring session as set by the developer. The default state of many document authoring tools is an editing-view.

prompt

prompt

properties, values, and defaults

• default value : The value given to a property by a user agent at installation.

public-key infrastructure

publishing

pure decoration

serving only an aesthetic purpose, providing no information, and having no functionality

Text is only purely decorative if the words can be rearranged or substituted without changing their purpose.

The cover page of a dictionary has random words in very light text in the background.

range

real-time event

• real-time events

event that a) occurs at the same time as the viewing and b) is not completely generated by the content

A Webcast of a live performance (occurs at the same time as the viewing and is not prerecorded).

An on-line auction with people bidding (occurs at the same time as the viewing).

Live humans interacting in a virtual world using avatars (is not completely generated by the content and occurs at the same time as the viewing).

recognize

reflowable content

region

• regions

perceivable, programmatically determined section of content

In HTML, any area designated with a landmark role would be a region.

relationships

meaningful associations between distinct pieces of content

relationships

relative luminance

the relative brightness of any point in a colorspace, normalized to 0 for darkest black and 1 for lightest white

Before May 2021 the value of 0.04045 in the definition was different (0.03928). It was taken from an older version of the specification and has been updated. It has no practical effect on the calculations in the context of these guidelines.

Almost all systems used today to view Web content assume sRGB encoding. Unless it is known that another color space will be used to process and display the content, authors should evaluate using sRGB colorspace. If using other color spaces, see Understanding Success Criterion 1.4.3.

If dithering occurs after delivery, then the source color value is used. For colors that are dithered at the source, the average values of the colors that are dithered should be used (average R, average G, and average B).

Tools are available that automatically do the calculations when testing contrast and flash.

A MathML version of the relative luminance definition is available.

relative time units

relied upon (technologies that are)

the content would not conform if that technology is turned off or is not supported

rendered content

• content specified by the author
• dynamic content created or altered by scripts
• content inserted by the user agent (e.g. repair text and security warnings on links)
• content inserted by style sheets or markup (e.g. number or letter preceding an ordered list item, the CSS content property)

repair (accessibility)

• manual repair: Where the repairs are carried out by authors. This includes the case where authors are aided by instructions or guidance provided by the authoring tool, but where authors carry out the actual repair procedure;
• semi-automated repair: Where the repairs are partially carried out by the authoring tool, but where authors' input or judgment is still required to complete the repair; and
• automated repair: Where the repairs are carried out automatically by the authoring tool without any intervention by authors.

repair content, repair text

• Erroneous or incomplete content (e.g. ill-formed markup, invalid markup, or missing alternative content that is required by format specification);
• Missing resources for handling or rendering content (e.g. the user agent lacks a font family to display some characters, or the user agent does not implement a particular scripting language).

restrictions, restricted web content authoring

robot

• robot
• robots
• web robot
• web robots

role

text or number by which software can identify the function of a component within Web content

A number that indicates whether an image functions as a hyperlink, command button, or check box.

role

same functionality

same result when used

A submit "search" button on one Web page and a "find" button on another Web page may both have a field to enter a term and list topics in the Web site related to the term submitted. In this case, they would have the same functionality but would not be labeled consistently.

same relative order

same position relative to other items

Items are considered to be in the same relative order even if other items are inserted or removed from the original order. For example, expanding navigation menus may insert an additional level of detail or a secondary navigation section may be inserted into the reading order.

satisfies a success criterion

• satisfies

the success criterion does not evaluate to 'false' when applied to the page

screen reader

• screen reader
• screen readers

script

section

a self-contained portion of written content that deals with one or more related topics or thoughts

A section may consist of one or more paragraphs and include graphics, tables, lists and sub-sections.

selection

sequential keyboard access

set of web pages

collection of web pages that share a common purpose and that are created by the same author, group or organization

Examples include a publication which is split across multiple Web pages, where each page contains one chapter or other significant section of the work. The publication is logically a single contiguous unit, and contains navigation features that enable access to the full set of pages.

Different language versions would be considered different sets of Web pages.

sign language

a language using combinations of movements of the hands and arms, facial expressions, or body positions to convey meaning

sign language interpretation

translation of one language, generally a spoken language, into a sign language

True sign languages are independent languages that are unrelated to the spoken language(s) of the same country or region.

single pointer

pointer input that operates with one point of contact with the screen, including single taps and clicks, double-taps and clicks, long presses, and path-based gestures

source text

spam filter

• spam filter
• spam filtering

specific sensory experience

a sensory experience that is not purely decorative and does not primarily convey important information or perform a function

Examples include a performance of a flute solo, works of visual art etc.

spider

• spider
• spiders

state

• states

dynamic property expressing characteristics of a user interface component that may change in response to user action or automated processes

States do not affect the nature of the component, but represent data associated with the component or user interaction possibilities. Examples include focus, hover, select, press, check, visited/unvisited, and expand/collapse.

status message

• status messages

change in content that is not a change of context, and that provides information to the user on the success or results of an action, on the waiting state of an application, on the progress of a process, or on the existence of errors

structure

1. The way the parts of a Web page are organized in relation to each other; and
2. The way a collection of Web pages is organized

style properties

• user agent default styles: The default style property values applied in the absence of any author or user styles. Some web content technologies specify a default rendering; others do not.
• author styles: Style property values that are set by the author as part of the content (e.g. in-line styles, author style sheets).
• user styles: Style property values that are set by the user (e.g. via user agent interface settings, user style sheets).

style property

• style properties

property whose value determines the presentation (e.g. font, color, size, location, padding, volume, synthesized speech prosody) of content elements as they are rendered (e.g. onscreen, via loudspeaker, via braille display) by user agents

Style properties can have several origins:

• User agent default styles: The default style property values applied in the absence of any author or user styles. Some web content technologies specify a default rendering, others do not;
• Author styles: Style property values that are set by the author as part of the content (e.g. in-line styles, author style sheets);
• User styles: Style property values that are set by the user (e.g. via user agent interface settings, user style sheets)

style sheet

• user style sheet: Style sheets that are not provided by the web content author. The user interface for configuring user style sheets can be targeted at advanced users.
• author style sheet: Style sheets specified by the author, resulting in author styles.

supplemental content

• supplementary content

additional content that illustrates or clarifies the primary content

An audio version of a Web page.

An illustration of a complex process.

A paragraph summarizing the major outcomes and recommendations made in a research study.

synchronize

synchronized media

audio or video synchronized with another format for presenting information and/or with time-based interactive components, unless the media is a media alternative for text that is clearly labeled as such

target

• targets

region of the display that will accept a pointer action, such as the interactive area of a user interface component

If two or more touch targets are overlapping, the overlapping area should not be included in the measurement of the target size, except when the overlapping targets perform the same action or open the same page.

target offset

• target offsets

New

the distance measured from the farthest point of a target to the nearest point of the second target. Offset includes the target and spacing around the target. The target offset from A to B may be different then the offset from B to A, if the size of these targets differ.

technology (Web content)

• technologies
• web technology
• web content technology
• web content technologies

mechanism for encoding instructions to be rendered, played or executed by user agents

As used in these guidelines "Web Technology" and the word "technology" (when used alone) both refer to Web Content Technologies.

Web content technologies may include markup languages, data formats, or programming languages that authors may use alone or in combination to create end-user experiences that range from static Web pages to synchronized media presentations to dynamic Web applications.

Some common examples of Web content technologies include HTML, CSS, SVG, PNG, PDF, Flash, and JavaScript.

technology (web content technology)

technology (web content)

template

• accessible templates (WCAG): Templates that can be filled in to create web content that meets the WCAG 2.0 success criteria (Level A, AA or AAA), when both of the following are true:
  1. The author correctly follows any instructions provided (e.g. correctly responding to prompts, correctly replacing highlighted placeholders); and
  2. No further authoring occurs
  Note: Under these conditions, some templates will result in completely empty documents, which are considered accessible by default.

template selection mechanism

text

sequence of characters that can be programmatically determined, where the sequence is expressing something in human language

text

• non-text content : Any content that is not a sequence of characters that can be programmatically determined or where the sequence is not expressing something in human language Note: This includes ASCII Art (which is a pattern of characters), emoticons, leetspeak (which uses character substitution), and images representing text.
• blocks of text : More than one sentence of text [ based on WCAG definition: blocks of text]

text alternative

Text that is programmatically associated with non-text content or referred to from text that is programmatically associated with non-text content. Programmatically associated text is text whose location can be programmatically determined from the non-text content.

An image of a chart is described in text in the paragraph after the chart. The short text alternative for the chart indicates that a description follows.

Refer to Understanding Text Alternatives for more information.

text transcript

time limit

top-level viewport

tutorial

up-event

platform event that occurs when the trigger stimulus of a pointer is released

The up-event may have different names on different platforms, such as "touchend" or "mouseup".

used in an unusual or restricted way

words used in such a way that requires users to know exactly which definition to apply in order to understand the content correctly

The term "gig" means something different if it occurs in a discussion of music concerts than it does in article about computer hard drive space, but the appropriate definition can be determined from context. By contrast, the word "text" is used in a very specific way in WCAG 2.1, so a definition is supplied in the glossary.

user agent

user agent

• user agents

any software that retrieves and presents Web content for users

Web browsers, media players, plug-ins, and other programs — including assistive technologies — that help in retrieving, rendering, and interacting with Web content.

user agent

• platform-based user agent, native user agent: User agents that run on non-web platforms (operating systems and cross-OS platforms, such as Java) and perform content retrieval, rendering and end-user interaction facilitation themselves (e.g. Firefox, Internet Explorer, Chrome, Opera, Windows Media Player, QuickTime Pro, RealPlayer).
• embedded user agent, plug-in : User agents that "plug-in" to other user agents or applications (e.g. media player plug-in for a web browser, web view component). Embedded user agents can establish direct connections with the platform (e.g. communication via platform accessibility services). See user agent add-on.
• web-based user agent : User agents that have user interfaces that are implemented using web content technologies and are accessed by users via a user agent. Web-based user agents transform content into web content technologies that the host user agent can render (e.g.web-based ePub reader, web-based video player).

• Desktop web browsers (e.g. Internet Explorer, Firefox, Chrome, Safari, Opera)
• Mobile web browsers (e.g. Firefox, Chrome, Safari, Android Browser, Opera Mini, Atomic Web, Puffin)
• Browser plug-ins (e.g. QuickTime Plug-in for Firefox, Acrobat Reader Plug-in for Internet Explorer, Shockwave Plug-in for Chrome)
• Web view components (e.g. Webkit Webview component, Web Tools Platform Plug-in for Eclipse, UIWebView for iOS)
• Authoring tools that render the web content being edited (e.g. Word, Dreamweaver, HTML-Kit)

• Operating environments or software bundles that include platform-based user agents (e.g. Windows, OS X, KDE, iOS), though the included user agents themselves are covered by UAAG 2.0.
• General-purpose platforms or toolkits that don't use web technologies, even though they can be used by user agents for other purposes (e.g. GNOME, KDE, .NET Framework/CLR).
• Narrow-purpose platform-based or web applications (e.g. online ticket booking applications).
• Authoring tools that only display a source view of the web content being edited (e.g. Notepad, Vim).

user agent

• In-Market User Agent: A user agent that can be procured by members of the public (free or otherwise). Usually, an in-market user agent will be a separate software from the authoring tool; however, sometimes a software may combine user agent and authoring tool functionality. These cases include:
  • Preview-Only: If the user agent can only render web content that it receives from the associated authoring functionality, then the software is an authoring tool with a preview feature. Such preview-only features are not considered in-market user agents.
  • User Agent with Authoring Tool Mode: If the user agent functionality must retrieve and open web content before it can be sent to the authoring tool functionality, then the software is a user agent with an authoring tool mode. If the user agent is used to preview content produced by the authoring tool mode, then it is to be considered an in-market user agent.
  • Combined User Agent/Authoring Tool: A user agent in which the default mode of user interaction enables editing the web content. These tools do not need previews because the author is already experiencing the content in the same way as end users.

user agent add-on (add-in, extension, plug-in)

• modify the content before the user agent renders it (e.g. to add highlights if certain types of alternative content are present), and
• modify the user agent's own user interface (e.g. add a headings view).

user inactivity

any continuous period of time where no user actions occur

The method of tracking will be determined by the web site or application.

user interface

• user agent user interface (UA user interface): The controls (e.g. menus, buttons, prompts, native audio/video player controls, and other components for input and output) and mechanisms (e.g. selection and focus) provided by the user agent that are not created on the basis of the author-supplied content. The UA user interface can include extensions that become part of the UA user interface (e.g. toolbars, additional menus).

• content user interface: The user interface that emerges from the user agent rendering of the author-supplied content. It includes all rendered content (e.g. text, headings, enabled elements, disabled elements, author-supplied audio/video controls).

  Note: There can be a mix of recognized and unrecognized user interface controls depending on the author-supplied content.

user interface component

• user interface components

a part of the content that is perceived by users as a single control for a distinct function

Multiple user interface components may be implemented as a single programmatic element. "Components" here is not tied to programming techniques, but rather to what the user perceives as separate controls.

User interface components include form elements and links as well as components generated by scripts.

What is meant by "component" or "user interface component" here is also sometimes called "user interface element".

An applet has a "control" that can be used to move through content by line or page or random access. Since each of these would need to have a name and be settable independently, they would each be a "user interface component."

user interface component

user interface control

user-controllable

data that is intended to be accessed by users

This does not refer to such things as Internet logs and search engine monitoring data.

Name and address fields for a user's account.

video

the technology of moving or sequenced pictures or images

Video can be made up of animated or photographic images, or both.

video

video

video-only

a time-based presentation that contains only video (no audio and no interaction)

view

• rendered view : A view where content is presented such that it is rendered, played or executed. There are two sub-types:
  • In conventionally rendered views the content is rendered, played or executed according to the web content technology specification. This is the default view of most user agents.
  • In unconventionally rendered views the content is rendered quite differently than specified in the technology specification (e.g. rendering an audio file as a graphical wavefront).
• source view : A view where the web content is presented without being rendered, played or executed. The source view can be plain text (i.e. "View Source") or it can include some other organization (e.g. presenting the markup in a tree).
• outline view : A view where only a subset of the rendered content is presented, usually composed of labels or placeholders for important structural elements. The important structural elements will depend on the web content technology, but can include headings, table captions, and content sections.

view

• editing-views: Views in which some or all of the content is editable; or
• previews: Views in which no authoring actions are provided (i.e. the view is not editable). Previews are provided to present the web content being edited by the authoring tool as it would appear to end users of user agents. Previews may be implemented using actual in-market user agents, but this is not necessary.

• source views : The content is presented in unrendered form (e.g. plain text editors); or
• rendered views: Content renderings (conventional, unconventional or partial) are presented; or
• property views: Only properties of the content are presented. The authoring tool then uses these properties to automatically generate the content to be published (e.g. CMS calendar widget that generates a calendar from the numeric month and year).

viewport

object in which the user agent presents content

The user agent presents content through one or more viewports. Viewports include windows, frames, loudspeakers, and virtual magnifying glasses. A viewport may contain another viewport (e.g., nested frames). Interface components created by the user agent such as prompts, menus, and alerts are not viewports.

This definition is based on User Agent Accessibility Guidelines 1.0 Glossary [[UAAG10]].

viewport

viewport dimensions

viewport size

The viewport size is the width and height at which a page is rendered. The viewport size is equal to the innerWidth and innerHeight of the window of the top-level browsing context.

Note: The viewport size is not to be confused with the "resolution" of the operating system. Often a browser will be a single window in the operating system, with a width and height different from the resolution of the operating system. Often browsers also include additional user interface components, such as a URL bar, tab bar, and a bookmarks bar. None of these are included in the viewport size. In full screen mode the viewport size might be the same as the resolution of the operating system.

Note: The viewport size includes, if rendered, all scrollbars.

visual track

visual-only

visually customized

the font, size, color, and background can be set

voice browser

web resource

workflow