Understandable principals include:
- Make text readable and understandable.
- Make content appear and operate in predictable ways.
- Help users avoid and correct mistakes.
Guideline 3.1
Readable: Make text content readable and understandable
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Guideline Number |
Level |
Recommendations |
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A |
The language of the page is identified using the HTML lang attribute (<html lang="en">, for example). |
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AA |
The language of page content that is in a different language is identified using the lang attribute (e.g., <blockquote lang="es">). |
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AAA |
Words that may be ambiguous, unknown, or used in a very specific way are defined through adjacent text, a definition list, a glossary, or other suitable methods. |
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AAA |
Expansions for abbreviations are provided by expanding or explaining the definition the first time it is used, using the <abbr> element, or linking to a definition or glossary. NOTE: WCAG 2.0 gives no exception for regularly understood abbreviations (e.g., "HTML" on a web design site must always be expanded). |
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AAA |
A more understandable alternative is provided for content that is more advanced than can be reasonably read by a person with roughly 9 years of primary education. |
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AAA |
If the pronunciation of a word is vital to understand that word, its pronunciation is provided immediately following the word or via a link or glossary. |
Guideline 3.2
Predictable: Make Web pages appear and operate in predictable ways
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Guideline Number |
Level |
Recommendations |
|
A |
When a page element receives focus, it does not result in a substantial change to the page, the spawning of a pop-up window, an additional change of keyboard focus, or any other change that could confuse or disorient the user. |
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A |
When a user inputs information or interacts with a control, it does not result in a substantial change to the page, the spawning of a pop-up window, an additional change of keyboard focus, or any other change that could confuse or disorient the user unless the user is informed of the change ahead of time. |
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AA |
Navigation links that are repeated on web pages do not change order when navigating through the site. |
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AA |
Elements that have the same functionality across multiple web pages are consistently identified. For example, a search box at the top of the site should always be labeled the same way. |
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AAA |
Substantial changes to the page, the spawning of pop-up windows, uncontrolled changes of keyboard focus, or any other change that could confuse or disorient the user must be initiated by the user. Alternatively, the user is provided an option to disable such changes. |
Guideline 3.3
Input Assistance: Help users avoid and correct mistakes
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Guideline Number |
Level |
Recommendations |
|
A |
Required form elements or form elements that require a specific format, value, or length provide this information within the element's label. If utilized, form validation errors are presented in an efficient, intuitive, and accessible manner. The error is clearly identified, quick access to the problematic element is provided, and user is allowed to easily fix the error and resubmit the form. |
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A |
Sufficient labels, cues, and instructions for required interactive elements are provided via instructions, examples, properly positioned form labels, and/or fieldsets/legends. |
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AA |
If an input error is detected (via client-side or server-side validation), provide suggestions for fixing the input in a timely and accessible manner. |
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AA |
If the user can change or delete legal, financial, or test data, the changes/deletions can be reversed, verified, or confirmed. |
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AAA |
Provide instructions and cues in context to help inform completion and submission. |
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AAA |
If the user can submit information, the submission is reversible, verified, or confirmed. |