Proposed Document has a landmark with non-repeated content
Description
This rule checks that each page has an element with a landmark semantic role starting with non-repeated content
Applicability
This rule applies to any HTML web page.
Expectations
Within each test target, either there is no non-repeated content after repeated content or there exists an element for which all the following are true:
- the element is an inheriting semantic
landmark
; and - the first perceivable content (in tree order in the flat tree) which is an inclusive descendant of the element is non-repeated content after repeated content; and
- the element is included in the accessibility tree.
Assumptions
- This rule assumes that landmarks are intended to users of Assistive Technologies and are not necessarily rendered in a visible way. Therefore, it does not require the main landmark to be visible. Similarly, technique ARIA11: Using ARIA landmarks to identify regions of a page does not require landmarks to be visible or have visible content.
Accessibility Support
Marking content with landmarks is sufficient to pass Success Criterion 2.4.1 Bypass blocks. However, this will only benefit users who can actually navigate using landmark roles (such a functionality is usually provided by assistive technologies, but could also be provided by browsers or browsers plugins). Users without any possibility for landmarks navigation will be left without way of bypassing blocks of repeated content and will still experience accessibility issues. Therefore, it is recommended to provide other ways of bypassing blocks.
Background
Most of the time, this rule passes by enclosing the primary content of the page in a main
landmark.
Technique ARIA11: Using ARIA landmarks to identify regions of a page only checks that landmarks are correctly used, but does not check whether landmarks could have been used and were omitted. Therefore, failing this rule (not having enough landmarks) does not necessarily fail that technique, and it is not listed as an accessibility mapping.
Bibliography
- Technique ARIA11: Using ARIA landmarks to identify regions of a page
- ARIA Landmarks Example
- CSS scoping (work in progress)
- The
main
role
Accessibility Requirements Mapping
This rule is not required for conformance.
Input Aspects
The following aspects are required in using this rule.
Test Cases
Passed
Passed Example 1
In this document, the main
element has a semantic role of main
and is included in the accessibility tree.
<html>
<head>
<title>The Three Kingdoms, Chapter 1</title>
</head>
<body>
<nav id="chapters-navigation">
<ol>
<li><a>Chapter 1</a></li>
<li><a href="/test-assets/bypass-blocks-cf77f2/chapter2.html">Chapter 2</a></li>
</ol>
</nav>
<main>
<p>
Unity succeeds division and division follows unity. One is bound to be replaced by the other after a long span
of time.
</p>
</main>
</body>
</html>
Passed Example 2
In this document the div
element has a semantic role of main
and is included in the accessibility tree.
<html>
<head>
<title>The Three Kingdoms, Chapter 1</title>
</head>
<body>
<nav id="chapters-navigation">
<ol>
<li><a>Chapter 1</a></li>
<li><a href="/test-assets/bypass-blocks-cf77f2/chapter2.html">Chapter 2</a></li>
</ol>
</nav>
<div role="main">
<p>
Unity succeeds division and division follows unity. One is bound to be replaced by the other after a long span
of time.
</p>
</div>
</body>
</html>
Passed Example 3
This document has several elements with a role of main
, at least one of them is included in the accessibility tree.
<html>
<head>
<title>Comparing translations of the Romance of the Three Kingdoms, Chapter one</title>
</head>
<body>
<nav id="chapters-navigation">
<ol>
<li><a>Chapter 1</a></li>
<li><a href="/test-assets/bypass-blocks-cf77f2/chapter2.html">Chapter 2</a></li>
</ol>
</nav>
<main aria-label="Translation by Charles Henry Brewitt-Taylor (1925)" aria-hidden="true">
<p>
The world under heaven, after a long period of division, tends to unite; after a long period of union, tends to
divide.
</p>
</main>
<main aria-label="Translation by Moss Roberts (1976)">
<p>The empire, long divided, must unite; long united, must divide. Thus it has ever been.</p>
</main>
<main aria-label="Translation by Yu Sumei (2014)" aria-hidden="true">
<p>
Unity succeeds division and division follows unity. One is bound to be replaced by the other after a long span
of time.
</p>
</main>
</body>
</html>
Passed Example 4
This document has no non-repeated content after repeated content.
<html>
<head>
<title>The Three Kingdoms, Chapter 1</title>
</head>
<body>
<p>
Unity succeeds division and division follows unity. One is bound to be replaced by the other after a long span of
time.
</p>
</body>
</html>
Failed
Failed Example 1
This document has no element with a landmark role.
<html>
<head>
<title>The Three Kingdoms, Chapter 1</title>
</head>
<body>
<div id="chapters-navigation">
<ol>
<li><a>Chapter 1</a></li>
<li><a href="/test-assets/bypass-blocks-cf77f2/chapter2.html">Chapter 2</a></li>
</ol>
</div>
<p>
Unity succeeds division and division follows unity. One is bound to be replaced by the other after a long span of
time.
</p>
</body>
</html>
Failed Example 2
This document has no element with a landmark role after its repeated content. The element with a landmark role does not contain any non-repeated content after repeated content.
<html>
<head>
<title>The Three Kingdoms, Chapter 1</title>
</head>
<body>
<nav id="chapters-navigation">
<ol>
<li><a>Chapter 1</a></li>
<li><a href="/test-assets/bypass-blocks-cf77f2/chapter2.html">Chapter 2</a></li>
</ol>
</nav>
<p>
Unity succeeds division and division follows unity. One is bound to be replaced by the other after a long span of
time.
</p>
</body>
</html>
Failed Example 3
This document has a main
landmark, but it is not included in the accessibility tree.
<html>
<head>
<title>The Three Kingdoms, Chapter 1</title>
</head>
<body>
<nav id="chapters-navigation">
<ol>
<li><a>Chapter 1</a></li>
<li><a href="/test-assets/bypass-blocks-cf77f2/chapter2.html">Chapter 2</a></li>
</ol>
</nav>
<main aria-hidden="true">
<p>
Unity succeeds division and division follows unity. One is bound to be replaced by the other after a long span
of time.
</p>
</main>
</body>
</html>
Inapplicable
Inapplicable Example 1
This document is not an HTML web page.
<svg xmlns="http://www.w3.org/2000/svg">
<title>This is an SVG</title>
</svg>
Glossary
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.
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.
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.
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.
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.
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
orpresentation
; or - it is an
img
element with analt
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.
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.
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.
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
orpresentation
.
Perceivable content corresponds to nodes that contain information and are perceived by some categories of users.
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
ofnone
; or - has an
aria-hidden
attribute set totrue
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:
- 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.
- Explicit If the element has an explicit role, then its semantic role is its explicit role.
- 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
.
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.
For more details, see examples of visible.
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.
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.
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.