`role=main` Should appear on the main content not significant elements.

[Muhnad]

in AX_ARIA_05: role=main should only appear on significant elements.

and in W3

The main content section of a document includes content that is unique to that document and excludes content that is repeated across a set of documents such as site navigation links, copyright information, site logos and banners and search forms (unless the document or applications main function is that of a search form).

Authors MUST NOT include more than one main element in a document. Note: Authors are advised to use ARIA role="main" attribute on the main element until user agents implement the required role mapping.

[jesse76424]

Fix computation of input[type="image"] text properties (