WCAG Understandable Success Criteria

Principle 3: Understandable Guidelines

WCAG Understandable Success Criteria
Information and the operation of user interface must be understandable. This means that users must be able to understand the information as well as the operation of the user interface. Page Titles must be unique and meaningful. Links and Buttons must have concise and clearly marked text labels. Images must have descriptive alternative text. The page foreground and background – and icons – must have contrasting colours for low vision users. The web page must have clearly defined user instructions, and a separation of information content.

Guideline 3.1 Readable

Make text content readable and understandable. The first success criteria is to define the language of the page. This will ensure that content developers provide information in the web page that user agents need to present text and other linguistic content correctly. Both assistive technologies and conventional user agents can render text more accurately when the language of the web page is identified. Screen readers can load the correct pronunciation rules. Visual browsers can display characters and scripts correctly. Media players can show captions correctly. As a result, users with disabilities will be better able to understand the content.

Be shure to include a definition for words used in an unusual way or as an abbreviation (such as a link to a glossary or within the text context). Often words or characters have different meanings, each with its own pronunciation. The meaning of such words or characters can usually be determined from the context of the sentence. However, for more complex or ambiguous sentences, or for some languages, the meaning of the word cannot be easily determined or determined at all without knowing the pronunciation. When the sentence is read aloud and the screen reader reads the word using the wrong pronunciation, it can be even more difficult to understand than when read visually. When words are ambiguous or indeterminate unless the pronunciation is known, then providing some means of determining the pronunciation is needed.

Guideline 3.2 Predictable

Make web pages appear and operate in predictable ways. That is, ensure that functionality is predictable as visitors navigate their way through a document. Any component that is able to trigger an event when it receives focus must not change the context automatically (such as an automatically submitted form or automatically launching a new window, when a component receives focus). Changes in context can confuse users who do not easily perceive the change or are easily distracted by changes. Changes of context are appropriate only when it is clear that such a change will happen in response to the user’s action. So, clicking on links or tabs in a tab control is activating the control, not changing the setting of that control.

Also, it is important to design web pages with consistent presentation and layout for users who interact with repeated content within a set of web pages and need to locate specific information or functionality more than once. Individuals with low vision who use screen magnification to display a small portion of the screen at a time often use visual cues and page boundaries to quickly locate repeated content.

Guideline 3.3 Input Assistance

Ensure that users are aware that an error has occurred and can determine what is wrong. The error message should be as specific as possible. In the case of an unsuccessful form submission, re-displaying the form and indicating the fields in error is insufficient for some users to perceive that an error has occurred. Screen reader users, for example, will not know there was an error until they encounter one of the indicators. They may abandon the form altogether before encountering the error indicator, thinking that the page simply is not functional.

When possible ensure that users receive appropriate suggestions for correction of an input error. Content authors must present instructions or labels that identify the controls in a form so that users know what input data is expected. Instructions or labels may also specify data formats for fields especially if they are out of the customary formats or if there are specific rules for correct input. Users with disabilities may be more likely to make mistakes. People with reading disabilities may transpose numbers and letters, and those with motor disabilities may hit keys by mistake. Providing the ability to reverse actions allows users to correct a mistake that could result in serious consequences. Providing the ability to review and correct information gives the user an opportunity to detect a mistake before taking an action that has serious consequences. Help users avoid making mistakes by Using context-sensitive help, users can find out how to perform an operation without losing track of what they are doing.