Accessibility Checking for Large Sites

The screen orientation (such as portrait or landscape) of mobile applications should not be restricted to a single mode. Users should be able to shift the orientation of their device between portrait and landscape without losing readability. Additionally, upon opening a page, it should appear in the current orientation of the user.

Users of assistive technologies may not have access to orientation features on their devices or assistive technologies.

What this Accessibility Rule Checks

Unless a specific display orientation is important, content does not confine its view and functionality to a single display orientation, such as portrait or landscape.

Definition lists (dl) may only contain dt and dd groups, div, script, or template elements that are properly organized.

Screen readers have a particular method for reading definition lists. When such lists are not correctly marked up, screen reader output may be erroneous or confusing.

A list of definitions is used to explain the meaning of words or phrases. Using the dl element, the definition list is formatted. Within the list, each term is enclosed in its own dt element, and its definition is enclosed in the dd element that immediately follows.

What this Accessibility Rule Checks

Ensures that each dl element is correctly constructed.

To be valid, definition list items (dt and / or dd) must be enclosed by parent dl elements. This allows screen reader users to recognize the right hierarchy of the list’s information.

A definition list item is invalid if it is not surrounded by parent dl elements.

A definition list must adhere to a particular hierarchy. Using the dl element, a list is defined. It is followed by alternating sets of dt and dd elements, beginning with dt. dt elements define a term while dd elements denote a term’s description. Each group of dt components must be accompanied by a group of dd elements. In the definition list, only dt and dd items are permitted. If not followed, this hierarchy will render the list invalid.

What this Accessibility Rule Checks

Ensures that every child dd and dt element has a parent dl element.

The title element of the HTML document must not be empty in order to give users with an overview of its content.

Users using screen readers utilize page titles to obtain an overview of the page’s content. If a page lacks a title, navigating through it can soon become difficult and confusing for screen reader users. The title element of the page is the first item screen reader users hear when the page loads.

When they arrive at a page, screen reader users hear the page’s title first. If there is no title or if the title is not descriptive and unique, users of screen readers must read the page to discern its content and purpose.

What this Accessibility Rule Checks

Makes certain that each HTML document has a title tag associated with it.

The value supplied to active ID attributes on focusable elements must be unique to avoid assistive technology from overlooking the second instance. Active ID attributes may not be used more than once on focusable components inside the same document; assistive technology requires unique IDs for focusable active elements in order to differentiate between them.

Focusable components on a page are identified exclusively by the ID attribute. It is illogical to duplicate an active ID.

Duplicate active ID values compromise the accessibility of focusable elements, such as form labels, table header cells, and so on. Screen readers and client-side scripts will bypass all instances of repetition other than the first. Validating HTML files aids in preventing and eliminating potential sources of accessibility issues, so long as accessibility is not compromised.

Those who have expertise with client-side scripting are aware that when an active ID is reused, the only instance that is normally acted upon by the script is the first. Similarly, assistive technology may only appropriately reference the first active ID when mentioning it.

What this Accessibility Rule Checks

Ensures that each page element with an active ID and a focusable state has a unique value.

tabindex="-1" cannot be present in <frame> and <iframe> elements with focusable content.

The browser is unable to move the focus to the content included in a frame when it has a negative tabindex. This stops keyboard navigation from skipping all of its content, and if the frame is scrollable, it also prevents the focus from moving to any element from which the frame may be scrolled.

What this Accessibility Rule Checks

Examine all frame and iframe elements that contain a negative tabindex value, such as tabindex="-1". If there are any such frames, make sure they don’t have nested frames that do contain focusable items.

To help screen reader users understand the contents of each frame or iframe element in the document, each element must have a distinct title.

A frame title is used by screen reader users to describe the contents of the frame. If the frames are not identified with a title element, navigating across frames and iframes can soon become challenging and confusing for users of this technology.

Users of screen readers can choose to display a list of all the titles for the frames on a page. Users can locate the frame they’re looking for more quickly by adding descriptive, distinctive labels. Without titles, moving between frames can become challenging and perplexing very quickly. Screen readers will instead provide information such as “frame,” “javascript,” the filename, or the URL if there is no title specified. This information won’t usually be particularly useful.

What this Accessibility Rule Checks

Make sure that the title attribute on every iframe and frame element is distinct and not empty.

When used in a document, the frame or iframe element’s title attribute must not be empty in order to provide context for users of screen reader software.

Users of screen readers depend on the title of a frame to describe its contents. If the HTML for a frame or iframe element lacks a title attribute, navigating within the element can be a frustrating and time-consuming experience for users of this technology.

Users of screen readers can see a list of the frames on a page and their respective titles. Providing each frame with a distinct, descriptive label facilitates easy navigation. Without titles, it’s easy to get lost trying to jump from one frame to the next. Screen readers will instead provide information like “frame,” “JavaScript,” the filename, or the URL if no title is provided. This data is unlikely to be useful in most situations.

What this Accessibility Rule Checks

Make sure the title attribute of every iframe and frame element is both distinct and not empty.

For multilingual screen reader users who would prefer a language other than the default, the HTML document element must have a valid lang property or match to a valid lang code.

The default language is chosen by users when setting up a screen reader. The screen reader uses the user’s default language preference when a webpage’s language is not specified. When people visit websites in more than one language and speak various languages, language settings become a problem. To ensure that website text is pronounced accurately, a language must be specified and validated.

Based on the pronunciation and traits of each language, screen readers employ distinct sound libraries for each one. If the documents state which language(s) to read when, screen readers can effortlessly switch between these language libraries. The screen reader will read the page in the user’s default language if the language is not set, which will result in an odd accent. When screen readers are utilizing the incorrect language library, nothing can be understood.

What this Accessibility Rule Checks

Ensures that the lang attribute is present in every HTML document.

For multilingual screen reader users who may prefer a language different than the default, the HTML content must contain a valid lang attribute or correlate to a valid lang code.

Users choose a default language when configuring a screen reader. If the language of a webpage is not provided, the screen reader uses the user’s default language. Language settings are a problem for users who speak different languages and visit websites in multiple languages. It is critical to declare a language and guarantee that it is valid in order for website text to be properly pronounced.

Screen readers employ various sound libraries for each language based on its pronunciation and characteristics. Screen readers can readily switch between these language libraries, but only if the documents specify which language(s) they should read. If no language is supplied, the screen reader reads the content in the user’s default language, which results in a perplexing accent! When screen readers use the incorrect language library, it is difficult to understand anything.

What this Accessibility Rule Checks

Ensures that every HTML document contains a lang or xml:lang property with a valid value.