Currently in the HTML AAM, header scoped to the body element is mapped to the banner role. Similarly, footer scoped to the body element is mapped to the contentinfo role. However, in both cases, they have platform mappings for each platform. So what's the point of the ARIA corresponding role? (rhetorical question)

The macOS and UIA mappings reflect what's in the Core AAM (modulo UIA's Localized Control Type), thus header and footer when scoped to the body element are treated as landmarks. But in ATK and MSAA+IA2, they are given different, non landmark roles. This means that the user experience may vary noticeably depending on platform, which is not ideal.

If header and footer, when scoped to the body element, really should be treated as if the elements had the stated ARIA role, then the MSAA+IA2 and ATK mappings are wrong and should be changed to reflect the mappings in the Core AAM. And if that is indeed the case, then wouldn't it make sense to make the following additional changes:

• For MSAA+IA2, ATK, and macOS replace the current mappings with "Use WAI-ARIA mapping"
• For UIA replace the current mappings with "Use WAI-ARIA mapping, but with Localized Control Type of $TYPE"