Role="banner" and contextual mapping

[rahimabdi]

There appears to be conflicting guidance on role="banner" mapping:

• MDN states that banner maps to generic in some contexts when it is a descendant of other sectioning elements: MDN ARIA banner role
• In core-aam 1.2 banner in all contexts maps the same across platform APIs
• ARIA 1.3 recommends a single banner element as a SHOULD but has a note that multiple banner elements are possible via DOM nesting or aria-owns: ARIA banner role

If banner has a contextual mapping, we'll need to update core-aam, our WPT contextual roles tests and perhaps provide clarification in the ARIA spec.

[JAWS-test]

MDN states that banner maps to generic in some contexts when it is a descendant of other sectioning elements: MDN ARIA banner role

I cannot find this statement at MDN. This statement is not made for ARIA role banner, but for HTML element header:

By default, the HTML's <header> element has an identical meaning to the banner landmark, unless it is a descendant of <aside>, <article>, <main>, <nav>, or <section>, at which point <header> exposes a generic role, and not the equivalent of the site-wide banner.

This is in accordance with https://w3c.github.io/html-aam/#el-header

[JAWS-test]

And even if MDN does not comply with the W3C specifications, the MDN documentation would generally have to be adapted and not our normative specification

[scottaohara]

@rahimabdi, JAWS-test is correct. role=banner is not a contextual role. the header element's role is either banner or generic (and only generic until #207 is implemented)

[rahimabdi]

Thank you @JAWS-test @scottaohara!