Getting Started - Usability Requirements

The following required and recommended standards will ensure that your website is easy to use, both for people using screen readers and the general public.

Required

• Three Flashes or Less
  Web pages must not contain anything that flashes more than three times in any one second period (i.e., has a frequency greater than 2Hz and lower than 55Hz), or the flashing is below the general flash and red flash thresholds. Techniques WCAG2
• Timing
  For each time limit that is set by the content, at least one of the following must be true: Techniques WCAG2
  
  

  • Turn off — The user must be allowed to turn off the time limit before encountering it; or
    
    
  • Adjust — The user must be allowed to adjust the time limit before encountering it over a wide range that is at least ten times the length of the default setting; or
    
    
  • Extend — The user must be warned before time expires and given at least 20 seconds to extend the time limit with a simple action (for example, "hit any key"), and the user is allowed to extend the time limit at least ten times; or
    
    
  • Real-time Exception — The time limit must be a required part of a real-time event (for example, an auction), and no alternative to the time limit is possible; or
    
    
  • Essential Exception — The time limit must be part of an activity where timing is essential (for example, time-based testing) and time limits cannot be extended further without invalidating the activity.
• Bypass Option
  A mechanism shall be provided that permits users to bypass blocks of content or navigation links that are repeated on multiple Web pages. Techniques WCAG2

Optional/Recommended

• Blinking
  Web pages shall be designed such that content does not blink for more than three seconds, or there shall be a method available to stop all blinking content in the Web page. Techniques WCAG2
• Pausing
  Moving, blinking, scrolling, or auto-updating information must allow pausing by the user unless it is part of an activity where timing or movement is essential. Content that is pure decoration must at least allow stopping by the user. Techniques WCAG2
• Language of Page
  Changes in the natural language of a document's text and any text equivalents (e.g., captions) must be clearly identified. For example, in HTML use the "lang" attribute. In XML, use "xml:lang". Techniques WCAG1 Techniques WCAG2
• Page Title
  Web pages must have descriptive titles. Techniques WCAG2
• Consistent Identification
  Components that have the same functionality within a set of Web pages must be identified consistently. Techniques WCAG2
• Consistent Navigation
  Navigational mechanisms that are repeated on multiple Web pages within a set of Web pages shall occur in the same relative order each time they are repeated, unless a change is initiated by the user. Techniques WCAG2
• Focus Order
  If a Web page can be navigated sequentially, focusable components shall receive focus in an order that follows information and relationships conveyed through presentation. Techniques WCAG2
• On Focus
  When any component receives focus, it must not initiate a change of context. Techniques WCAG2
• On Input
  Changing the setting of any user interface component must not automatically cause a change of context unless the user has been advised of the behavior before using the component. Techniques WCAG2
• Error Identification
  If an input error is automatically detected, the item that is in error must be identified and described to the user in text. Techniques WCAG2