4 Robust
Content must be robust enough that it can be interpreted by a wide variety of user agents, including assistive technologies.
4.1 Compatible
Maximize compatibility with current and future user agents, including assistive technologies.
4.1.1 Parsing (Obsolete and removed)
Conformance level: A
4.1.2 Name, Role, Value
Conformance level: A
Ensure that user interface components have clear names, roles, and states.
4.1.3 Status Messages
Conformance level: AA
Ensure status messages are available to assistive technologies without receiving focus.