Accessibility of web content requires semantic information about widgets, structures, and behaviors, in order to allow assistive technologies to convey appropriate information to persons with
disabilities. This specification provides an ontology of roles, states, and properties that define accessible user interface elements and can be used to improve the accessibility and
interoperability of web content and applications. These semantics are designed to allow an author to properly convey user interface behaviors and structural information to assistive
technologies in document-level markup. This version adds features new since WAI-ARIA 1.1 [wai-aria-1.1] to improve interoperability with assistive technologies to form a more consistent
accessibility model for [HTML] and [SVG2]. This specification complements both [HTML] and [SVG2].
This document is part of the WAI-ARIA suite described in the
WAI-ARIA Overview.
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expanding the accessibility information that can be supplied by the author;
requiring that supporting host languages provide full keyboard support that can be implemented in a device-independent way, for example, by telephones, handheld devices, e-book readers, and
televisions;
improving the accessibility of dynamic content generated by scripts; and
WAI-ARIA is a technical specification that provides a framework to improve the accessibility and interoperability of web content and applications. This document is primarily for developers
creating custom widgets and other web application components. Please see the WAI-ARIA Overview for links to related documents
for other audiences, such as
ARIA Authoring Practices Guide
that introduces developers to the accessibility problems that WAI-ARIA is intended to solve, the fundamental concepts, and the technical approach of WAI-ARIA.
This document currently handles two aspects of roles: user interface functionality and structural relationships. For more information and use cases, see
ARIA Authoring Practices Guide
for the use of roles in making interactive content accessible.
Roles defined by this specification are designed to support the roles used by platform accessibility APIs. Declaration of these roles on elements within dynamic web content is intended to support interoperability between the web content and assistive technologies that utilize
accessibility APIs.
The schema to support this standard has been designed to be extensible so that custom roles can be created by extending base roles. This allows user agents to support at least the base
role, and user agents that support the custom role can provide enhanced access. Note that much of this could be formalized in [XMLSCHEMA11-2]. However, being able to define similarities
between roles, such as baseConcepts and more descriptive definitions, would not be available in XSD.
WAI-ARIA 1.2 is a member of the
WAI-ARIA 1.2 suite that defines how to expose semantics of WAI-ARIA and other web
content languages to accessibility APIs.
1.1 Rich Internet Application Accessibility
The domain of web accessibility defines how to make web content usable by persons with disabilities. Persons with certain types of disabilities use assistive technologies (AT) to interact with content. Assistive technologies can transform the presentation of content into a format more suitable to the user, and can allow the user to interact in different ways.
For example, the user might need to, or choose to, interact with a slider widget via arrow keys, instead of dragging and dropping with a mouse. In order to accomplish this effectively, the
software needs to understand the semantics of the content. Semantics is the science of meaning; in this case, used to assign roles, states, and properties that apply to user interface
and content elements as a human would understand. For instance, if a paragraph is semantically identified as such, assistive technologies can interact with it as a unit separable from the
rest of the content, knowing the exact boundaries of that paragraph. An adjustable range slider or collapsible list (a.k.a. a tree widget) are more complex examples, in which various
parts of the widget have semantics that need to be properly identified for assistive technologies to support effective interaction.
New technologies often overlook semantics required for accessibility, and new authoring practices often misuse the intended semantics of those technologies. Elements that have one
defined meaning in the language are used with a different meaning intended to be understood by the user.
For example, web application developers create collapsible tree widgets in HTML using CSS and JavaScript even though HTML has no semantic tree element. To a non-disabled user,
it might look and act like a collapsible tree widget, but without appropriate semantics, the tree widget might not be perceivable to, or operable by, a person with a disability
because assistive technologies might not recognize the role. Similarly, web application developers create interactive button widgets in SVG using JavaScript even though SVG has no semantic
button element. To a non-disabled user, it might look and act like a button widget, but without appropriate semantics, the button widget might not be perceivable to, or
operable by, a person with a disability because assistive technologies might not recognize the role.
The incorporation of WAI-ARIA is a way for an author to provide proper semantics for custom widgets to make these widgets
accessible, usable, and interoperable with assistive technologies. This specification identifies the types of widgets and structures that are commonly recognized by accessibility products,
by providing an ontology of corresponding roles that can be attached to content. This allows elements with a given role to be understood as a particular widget or structural
type regardless of any semantics inherited from the implementing host language. Roles are a common property of platform
accessibility APIs which assistive technologies use to provide the user with effective presentation and interaction.
The Roles Model includes interaction widgets and elements denoting document structure. The Roles Model describes inheritance and details the attributes each role supports.
Information about mapping of roles to accessibility APIs is provided by the
Core Accessibility API Mappings [CORE-AAM-1.2].
Roles are element types and will not change with time or user actions. Role information is used by assistive technologies, through interaction with the user agent, to provide normal
processing of the specified element type.
States and properties are used to declare important attributes of an element that affect and describe interaction. They enable the user agent and operating system to properly handle
the element even when the attributes are dynamically changed by client-side scripts. For example, alternative input and output technology, such as screen readers and speech dictation
software, need to be able to recognize and effectively manipulate and communicate various interaction states (e.g., disabled, checked) to the user.
Figure 1 illustrates the relationship between user agents (e.g., browsers), accessibility APIs, and assistive technologies. It describes the "contract" provided by
the user agent to assistive technologies, which includes typical accessibility information found in the accessibility API for many of
our accessible platforms for GUIs (role, state, selection, event notification, relationship information, and descriptions). The DOM, usually HTML, acts as the data model and
view in a typical model-view-controller relationship, and JavaScript acts as the controller by manipulating the style and content of the displayed data. The user agent conveys relevant
information to the operating system's accessibility API, which can be used by any assistive technologies, such as screen readers.
Figure 1The contract model with accessibility APIs
Users of alternate input devices need keyboard accessible content. The new semantics, when combined with the recommended keyboard interactions provided in
ARIA Authoring Practices Guide, will allow alternate input solutions to facilitate command and control via an alternate input solution.
WAI-ARIA introduces navigational landmarks through its Roles Model and the
XHTML role landmarks, which can help persons with dexterity and vision impairments by providing for improved keyboard navigation.
WAI-ARIA can also be used to assist persons with cognitive learning disabilities. The additional semantics allow authors to
restructure and substitute alternative content as needed.
Assistive technologies need the ability to support alternative inputs by getting and setting the current value of widget states and properties. Assistive technologies also need
to determine what objects are selected and manage widgets that allow multiple selections, such as list boxes and grids.
Speech-based command and control systems can benefit from WAI-ARIA semantics like the role attribute to assist in
conveying audio information to the user. For example, upon encountering an element with a role of menu with child elements of role menuitem each containing text
content representing a different flavor, a speech system might state to the user, "Select one of three choices: chocolate, strawberry, or vanilla."
WAI-ARIA is intended to be used as a supplement for native language semantics, not a replacement. When the host language provides a
feature that provides equivalent accessibility to the WAI-ARIA feature, use the host language feature.
WAI-ARIA should only be used in cases where the host language lacks the needed role, state, and property
indicators. Use a host language feature that is as similar as possible to the WAI-ARIA feature, then refine the meaning by adding
WAI-ARIA. For instance, a multi-selectable grid could be implemented as a table, and then
WAI-ARIA used to clarify that it is an interactive grid, not just a static data table. This allows for the best possible fallback
for user agents that do not support WAI-ARIA and preserves the integrity of the host language semantics.
1.2 Target Audience
This specification defines the basic model for WAI-ARIA, including roles, states, properties, and values. It impacts several
audiences:
user agents that process content containing WAI-ARIA features;
Authoring tools that help authors create conforming content; and
Conformance checkers that verify appropriate use of WAI-ARIA.
Each conformance requirement indicates the audience to which it applies.
Although this specification is applicable to the above audiences, it is not specifically targeted to, nor is it intended to be the sole source of information for, any of these audiences. The
following documents provide important supporting information:
ARIA Authoring Practices Guide
addresses authoring recommendations for HTML, and is also of interest to developers of authoring tools and conformance checkers.
Assistive technologies use the enhanced information available in an accessibility API, or uses the WAI-ARIA markup
directly via the DOM, to convey semantic and interaction information to the user.
Aside from using WAI-ARIA markup to improve what is exposed to accessibility APIs, user agents behave as they would natively.
Assistive technologies react to the extra information in the accessibility API as they already do for the same information on non-web content. User agents that are not assistive
technologies, however, need do nothing beyond providing appropriate updates to the accessibility API.
The WAI-ARIA specification neither requires nor forbids user agents from enhancing native presentation and interaction behaviors on
the basis of WAI-ARIA markup. Mainstream user agents might expose
WAI-ARIA navigational landmarks (for example, as a dialog box or through a keyboard command) with the intention to facilitate
navigation for all users. User agents are encouraged to maximize their usefulness to users, including users without disabilities.
WAI-ARIA is intended to provide missing semantics so that the intent of the author can be conveyed to assistive technologies.
Generally, authors using WAI-ARIA will provide the appropriate presentation and interaction features. Over time, host languages can
add WAI-ARIA equivalents, such as new form controls, that are implemented as standard accessible user interface controls by the
user agent. This allows authors to use them instead of custom WAI-ARIA enabled user interface components. In this case the user
agent would support the native host language feature. Developers of host languages that implement WAI-ARIA are advised to continue
supporting WAI-ARIA semantics when they do not adversely conflict with implicit host language semantics, as
WAI-ARIA semantics more clearly reflect the intent of the author if the host language features are inadequate to meet the author's
needs.
1.4 Co-Evolution of WAI-ARIA and Host Languages
WAI-ARIA is intended to be used as an accessibility enhancement technology in markup-based host languages. Examples include
[HTML] and [SVG2], which both explicitly support the use of ARIA.
ARIA roles and properties clarify semantics to assistive technologies when authors create new types of objects, via style and script, that are not yet directly supported by the language of
the page, because the invention of new types of objects is faster than standardized support for them appears in web languages.
It is not appropriate to create objects with style and script when the host language provides a semantic element for that type of object. While
WAI-ARIA can improve the accessibility of these objects, accessibility is best provided by allowing the user agent to handle the
object natively. For example, it's better to use an h1 element in HTML than to use the heading role on a div element.
It is expected that, over time, host languages will evolve to provide semantics for objects that currently can only be declared with
WAI-ARIA. This is natural and desirable, as one goal of WAI-ARIA is to
help stimulate the emergence of more semantic and accessible markup. When native semantics for a given feature become available, it is appropriate for authors to use the native feature and
stop using WAI-ARIA for that feature. Legacy content can continue to use
WAI-ARIA, however, so the need for user agents to support
WAI-ARIA remains.
While specific features of WAI-ARIA might lose importance over time, the general possibility of
WAI-ARIA to add semantics to web pages is expected to be a persistent need. Host languages might not implement all the semantics
WAI-ARIA provides, and various host languages can implement different subsets of the features. New types of objects are continually
being developed, and one goal of WAI-ARIA is to provide a way to make such objects accessible, because authoring practices often
advance faster than host language standards. In this way, WAI-ARIA and host languages both evolve together but at different rates.
Some host languages exist to create semantics for features other than the user interface. For example, SVG expresses the semantics behind production of graphical objects, not of user
interface components that those objects can represent. Host languages might, by design, not provide native semantics that map to
WAI-ARIA features. In these cases, WAI-ARIA could be adopted as a
long-term approach to add semantic information to user interface components.
1.5 Authoring Practices
1.5.1 Authoring Tools
Many of the requirements in the definitions of WAI-ARIA roles, states, and properties can be checked
automatically during the development process, similar to other quality control processes used for validating code. To assist authors who are creating custom widgets, authoring tools can
compare widget roles, states, and properties to those supported in WAI-ARIA as well as those supported in related and
cross-referenced roles, states, and properties. Authoring tools can notify authors of errors in widget design patterns, and can also prompt developers for information that cannot be
determined from context alone. For example, a scripting library can determine the labels for the tree items in a tree view, but would need to prompt the author to label the entire tree. To
help authors visualize a logical accessibility structure, an authoring environment might provide an outline view of a web resource based on the
WAI-ARIA markup.
In both HTML and SVG, tabindex is an important way browsers support keyboard focus navigation for implementations of
WAI-ARIA; authoring and debugging tools can check to make sure tabindex values are properly set. For example, error
conditions can include cases where more than one treeitem in a tree has a tabindex value greater than or equal to 0, where tabindex is not set on any treeitem, or
where aria-activedescendant is not defined when the element with the role tree has a tabindex value of greater than or equal to 0.
1.5.2 Testing Practices and Tools
The accessibility of interactive content cannot be confirmed by static checks alone. Developers of interactive content should test for device-independent access to widgets and
applications, and should verify accessibility API access to all content and changes during user interaction.
1.6 Assistive Technologies
Programmatic access to accessibility semantics is essential for assistive technologies. Most assistive technologies interact with user agents, like other applications, through a recognized
accessibility API. Perceivable objects in the user interface are exposed to assistive technologies as accessible objects, defined by the accessibility API interfaces. To do this properly,
accessibility information – role, states, properties as well as contextual information – needs to be accurately conveyed to the assistive technologies through the accessibility API. When a
state change occurs, the user agent provides the appropriate event notification to the accessibility API. Contextual information, in many host languages like HTML, can be determined from the
DOM itself as it provides a contextual tree hierarchy.
While some assistive technologies interact with these accessibility APIs, others might access the content directly from the DOM. These technologies
can restructure, simplify, style, or reflow the content to help a different set of users. Common use cases for these types of adaptations might be the aging population, persons with
cognitive impairments, or persons in environments that interfere with use of their tools. For example, the availability of regional navigational landmarks can allow for a mobile device
adaptation that shows only portions of the content at any one time based on its semantics. This could reduce the amount of information the user needs to process at any one time. In other
situations it might be appropriate to replace a custom user interface control with something that is easier to navigate with a keyboard, or touch screen device.
2. Important Terms
This section is non-normative.
While some terms are defined in place, the following definitions are used throughout this document.
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 might 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.
Deprecated
A deprecated role, state, or property is one which has been
outdated by newer constructs or changed circumstances, and which might 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.
Defines
Used in an attribute description to denote that the value type is an integer,
number, or string.
Event from/to the host operating system via the accessibility API, notifying of a change of input focus.
Event
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.
An element or area matching the definition of focusable area in the HTML Specification.
Graphical Document
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).
Hidden
Indicates that the element is excluded from the accessibility tree and therefore not exposed to accessibility APIs.
Used in an attribute description to denote that the value type is an ID reference (identifying a single element) or
ID reference list (identifying one or more elements).
A type of region on a page to which the user might 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.
Live Region
Live regions are perceivable regions of a web page that are typically updated as a result of an external event. These regions are not always updated as a result of a user interaction and
can receive these updates even when they do not have focus. 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
Accessibility APIstate 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.
Nemeth Braille
The Nemeth Braille Code for Mathematics is a braille code for encoding mathematical and scientific notation. See
Nemeth Braille on Wikipedia.
Object
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.
In the context of programming, the instantiation of one or more classes and interfaces which define the general characteristics of similar objects. An object in an
accessibility API can represent one or more DOM objects. Accessibility APIs have defined interfaces
that are distinct from DOM interfaces.
Ontology
A description of the characteristics of classes and how they relate to each other.
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 can 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.
Relationship
A connection between two distinct things. Relationships can be of various types to indicate which object labels another, controls another, etc.
Role
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.
Semantics
The meaning of something as understood by a human, defined in a way that computers can process a representation of an object, such as