Proposed ARIA required owned elements

Description

This rule checks that an element with an explicit semantic role has at least one of its required owned elements.

Applicability

This rule applies to any HTML or SVG element that is included in the accessibility tree and has a WAI-ARIA 1.2 explicit semantic role with required owned elements, except if the element has an inclusive ancestor in the accessibility tree with an aria-busy attribute value of true.

Expectation

Each test target only owns elements with a semantic role from the required owned element list for the test target’s semantic role.

Note: The definition of owned by used in this rule is different than the definition of “owned element” in WAI-ARIA. See more in the owned by definition.

Assumptions

If the explicit semantic role on the target element is incorrectly used, and any relationships between elements are already programmatically determinable, failing this rule may not result in accessibility issues for users of assistive technologies, and it should then not be considered a failure under WCAG success criterion 1.3.1 Info and Relationships.

Accessibility Support

• User agents do not all have the same accessibility tree. Particularly the method of deriving which element owns which other elements varies between browsers. This can lead to different results for this rule, depending on which accessibility tree is used as input.
• aria-owns has limited support in some user agents.
• Assistive technologies are not consistent in how they handle situations where a required owned element has a missing or incorrect role. This can lead to situations where inaccurate owned elements behave as expected in one assistive technology, but not in another.
• Some user agents treat the value of aria-busy as case-sensitive.

Background

Some required owned elements are only valid if they themselves own (or “contain”) elements with a given semantic role. This is denoted by an arrow (meaning “containing”) in the role description. For example, the role menu has group → menuitemradio as one of its required owned elements, meaning that elements with a role of menu may only own elements with a role of group who themselves only own elements with a role of menuitemradio.

The applicability of this rule is limited to the WAI-ARIA 1.2 Recommendation roles. The WAI-ARIA Graphics Module and Digital Publishing WAI-ARIA Module (DPUB ARIA) 1.1 (Editors draft) do not include any required owned elements.

Note: Subclass roles of required owned elements are not automatically included as possible required owned elements. For example, the treeitem role is not a required owned elements for list, even though treeitem is a subclass role of listitem.

Bibliography

• Understanding Success Criterion 1.3.1: Info and Relationships
• Required Owned Element
• Owned Element

Accessibility Requirements Mapping

• 1.3.1 Info and Relationships (Level A)

  • Learn more about 1.3.1 Info and Relationships
  • Required for conformance to WCAG 2.0 and later on level A and higher.
  • Outcome mapping:
    • Any failed outcomes: success criterion is not satisfied
    • All passed outcomes: success criterion needs further testing
    • An inapplicable outcome: success criterion needs further testing

Input Aspects

The following aspects are required in using this rule.

• Accessibility tree
• CSS styling
• DOM Tree

Test Cases

Passed

Passed Example 1

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This element with the list role only owns elements with the listitem role. The listitem role is one of the required owned elements for list.

<div role="list">
	<span role="listitem">Item 1</span>
	<span role="listitem">Item 2</span>
</div>

Passed Example 2

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This element with the grid role only owns elements with the row role, and the element with the row role only owns elements with the cell role. The row role is one of the required owned elements for grid, and cell is one of the required owned elements for row.

<table role="grid">
	<tr role="row">
		<td role="cell">Item 1</td>
	</tr>
</table>

Passed Example 3

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This element with the menu role only owns elements with the menuitem, menuitemradio and menuitemcheckbox role. These roles are all required owned elements for menu. The element with the none role is not owned by the menu because it is not included in the accessibility tree.

<div role="menu">
	<li role="none"></li>
	<li role="menuitem">Item 1</li>
	<div role="menuitemradio" aria-checked="false">Item 2</div>
	<div role="menuitemcheckbox" aria-checked="false">Item 3</div>
</div>

Passed Example 4

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This element with the tablist role only owns elements with the tab role. The tab role is one of the required owned elements for tablist. The li element is ignored because it has an explicit semantic role of none.

<ul role="tablist">
	<li role="none">
		<span role="tab">Tab 1</span>
	</li>
</ul>

Passed Example 5

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This element with the list role only owns elements with the listitem role through the aria-owns attribute. The listitem role is one of the required owned elements for list.

Note: This test case follows the definition of owned by. If implemented differently, this definition could cause differences in outcome of this test case.

<div role="list" aria-owns="id1"></div>
<div id="id1" role="listitem">Item 1</div>

Passed Example 6

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This element with the menu role only owns an element with a group role. The group in turn owns an element with the menuitem role, and an element with the group role, in which each element has the menuitem role. ARIA group roles are allowed to own other elements with a group role.

<div role="menu">
	<div role="group">
		<span role="menuitem">Item 1</span>
		<div role="group">
			<span role="menuitem">Item 2</span>
			<span role="menuitem">Item 3</span>
		</div>
	</div>
</div>

Failed

Failed Example 1

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This element with the list role owns an element which is not a listitem required owned elements.

<div role="list">
	<span>Item 1</span>
</div>

Failed Example 2

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This element with the tablist role owns an element with the listitem role. The listitem role is not one of the required owned elements for tablist.

<ol role="tablist">
	<li role="listitem">Item 1</li>
</ol>

Failed Example 3

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This element with the list role owns an element with the listitem role, and one with the link role. The link role is not one of the required owned elements for list.

<div role="list">
	<li>Item 1</li>
	<span role="link">Item 2</span>
</div>

Failed Example 4

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This element with the grid role only owns elements with the row role, but the element with the row role does not own any of its required owned elements.

<div role="grid">
	<div role="row">
		<span>Item 1</span>
	</div>
</div>

Failed Example 5

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This element with the list role owns an element with the tab role through the aria-owns attribute. The tab role is not one of the required owned elements for list.

Note: This test case follows the definition of owned by. If implemented differently, this definition could cause differences in outcome of this test case.

<div role="list" aria-owns="id2"></div>
<div id="id2" role="tab">Tab 1</div>

Failed Example 6

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This element with the menu role only owns an element with a group role. The group in turn owns an element with the menuitem role, and an element with the group role, in which each element has the treeitem role. ARIA group roles are allowed to own other elements with a group role, but those nested group nodes must still meet the requirements.

<div role="menu">
	<div role="group">
		<span role="menuitem">Item 1</span>
		<div role="group">
			<span role="treeitem">Item 1</span>
			<span role="treeitem">Item 2</span>
		</div>
	</div>
</div>

Failed Example 7

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This element with the list role owns an element with the listitem role and an element with the group role, in which each element has the listitem role. The group role is no longer a required owned element for the list role.

<div role="list">
	<span role="listitem">Item 1</span>
	<div role="group">
		<span role="listitem">Item 2</span>
		<span role="listitem">Item 3</span>
	</div>
</div>

Inapplicable

Inapplicable Example 1

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This element with the list role is not included in the accessibility tree because the aria-hidden attribute is set to true.

<div role="list" aria-hidden="true"></div>

Inapplicable Example 2

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This ul element does not have an explicit semantic role.

<ul>
	<li>Item 1</li>
</ul>

Inapplicable Example 3

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This element with the progressbar role does not need required owned elements.

<div role="progressbar" aria-valuenow="20" aria-valuemin="0" aria-valuemax="100">20 %</div>

Inapplicable Example 4

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This element with the menu role has an aria-busy attribute set to true.

<ul role="menu" aria-busy="true">
	Loading
</ul>

Glossary

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.

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.

Focusable

An element is focusable if one or both of the following are true:

• the element is part of sequential focus navigation; or
• the element has a tabindex value that is not null.

Exception: Elements that lose focus during a period of up to 1 second after gaining focus, without the user interacting with the page the element is on, are not considered focusable.

Notes:

• The 1 second time span is an arbitrary limit which is not included in WCAG. Given that scripts can manage the focus state of elements, testing the focusability of an element consistently would be impractical without a time limit.
• The tabindex value of an element is the value of the tabindex attribute parsed using the rules for parsing integers. For the tabindex value to be different from null, it needs to be parsed without errors.

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).

Included in the accessibility tree

Elements included in the accessibility tree of platform specific accessibility APIs are exposed to assistive technologies. This allows users of assistive technology to access the elements in a way that meets 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.

Programmatically hidden elements are removed from the accessibility tree. However, some browsers will leave focusable elements with an aria-hidden attribute set to true in the accessibility tree. Because they are hidden, these elements are considered not included in the accessibility tree. This may cause confusion for users of assistive technologies because they may still be able to interact with these focusable elements using sequential keyboard navigation, even though the element should not be included in the accessibility tree.

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.

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.

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 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.

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

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

Note: The HTML standard suggests setting the CSS display property to none for elements with the hidden attribute. While not required by HTML, all modern browsers follow this suggestion. Because of this the hidden attribute is not used in this definition. In browsers that use this suggestion, overriding the CSS display property can reveal elements with the hidden attribute.

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.

WAI-ARIA specifications

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

• Accessible Rich Internet Applications (WAI-ARIA) 1.2
• 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.

Rule Versions

This is the first version of this ACT rule.

Implementations

This section is not part of the official rule. It is populated dynamically and not accounted for in the change history or the last modified date.

Implementation	Type	Consistency	Report
Alfa (fully automated) 0.57.2	Automated tool	Partial
Alfa (semi-automated) 0.57.2	Semi-automated tool	Partial
Axe DevTools Pro 4.37.1	Semi-automated tool	Consistent
Axe-core 4.8.1	Automated tool	Consistent
Equal Access Accessibility Checker 3.1.42-rc.0	Automated tool	Partial
QualWeb 3.0.0	Automated tool	Consistent
SortSite 6.45	Automated tool	Consistent
Total Validator 17.1.0	Linter	Consistent
Total Validator (+Browser) 17.3.0	Automated tool	Consistent

Useful Links

• Github issues related to this rule
• Open a new issue
• Propose a change to the rule