Principle 4: Content must be robust enough to work with current and future technologies.

Guideline 4.1 Ensure compatibility with current and future user agents (including assistive technologies)

Level 1 Success Criteria for Guideline 4.1

4.1.1 Delivery units can be parsed unambiguously and the relationships in the resulting data structure are also unambiguous. [How to meet 4.1.1]

4.1.2 (was 4.2.3) The role, state, and value can be programmatically determined for every user interface component of the web content that accepts input from the user or changes dynamically in response to user input or external events. [How to meet 4.1.2]

4.1.3 (was 4.2.4) The label of each user interface control that accepts input from the user can be programmatically determined and is explicitly associated with the control. [How to meet 4.1.3]

4.1.4 (was 4.2.5) The content and properties of user interface elements that can be changed via the user interface can also be directly changed programmatically. [How to meet 4.1.4]

Note: Some examples of standardized properties that typically can be changed by the user interface include its value, whether it is currently selected, and whether it currently has the focus.

Editorial Note: The working group is still considering whether this criterion should be included and, if so, at what level.

4.1.5 (was 4.2.6) Changes to content, structure, selection, focus, attributes, values, state, and relationships can be programmatically determined. [How to meet 4.1.5]

Level 2 Success Criteria for Guideline 4.1

(No level 2 success criteria for this guideline.)

Level 3 Success Criteria for Guideline 4.1

(No level 3 success criteria for this guideline.)

Guideline 4.1 (use-spec) Issues

Guideline 4.2 Ensure that content is accessible or provide an accessible alternative

Level 1 Success Criteria for Guideline 4.2

4.2.1 If content does not meet all level 1 success criteria, then an alternate version is available from the same URI that does meet all level 1 success criteria. [How to meet 4.2.1]

4.2.2 Content meets the following criteria even if the content uses a technology that is not in the chosen baseline: [How to meet 4.2.2]

  1. When content violates either the general flash threshold or thered flash threshold, users are warned in a way that they can avoid it.

  2. If the user can enter the content using the keyboard, then the user can exit the content using the keyboard.

Level 2 Success Criteria for Guideline 4.2

(No level 2 success criteria for this guideline.)

Level 3 Success Criteria for Guideline 4.2

4.2.3 (was 4.2.7) Content implemented using technologies outside of the chosen baseline satisfies all level 1 and 2 WCAG requirements supported by the technologies. [How to meet 4.2.3]

Techniques for Addressing Success Criterion 4.1.1

The following combinations of techniques are deemed to be sufficient by the WCAG Working Group for meeting success criterion 4.1.1.

Doing one or more of the following:

  • ensuring that delivery units can be parsed unambiguously by using one of the technology-specific techniques below. OR

  • Conforming to specifications OR

  • Validating delivery units