From ARIA issue #155
In HTML-AAM, UIA uses localized strings "header" and "footer" for both landmark and non-landmark instances of header and footer, differentiating between the two instances via LandmarkType.
In AX, the non-landmark instances are simply mapped to the AXGroup role with "group" as the localized string. The landmark instances of header and footer use "banner" and "footer" respectively. @cookiecrook, I'm assuming you're comfy with this, or do you want to follow suit and use "header" as the AXRoleDescription for the landmark instance of header?