Should structured descriptions be exposed in the accessibility tree?

[AmeliaBR]

Copying over two issues from the spec:

The strict exclusion of non-rendered metadata elements, including desc, from the accessibility tree means that their content will only be available as plain text, not as structured alternative representations that a user can navigate in browsing mode.

This contradicts the original intent of the SVG specifications, which allows these elements to include structured content, including HTML-namespaced content. The SVG 1 specifications had suggested that this could be alternatively presented as CSS-formated XML text, but this is not supported by the user agent/assistive technology combinations currently in use.

The CORE-AAM section on Relations requires that assistive technologies SHOULD provide a method to navigate to (and within) structured content referenced by aria-describedby. This would be difficult to implement with the current approach of not including non-rendered descriptive content in the accessibility tree. See w3c/core-aam#3

[brennanyoung]

Do you imagine something like aria-describedby pointing at a foreignObject (HTML) which would put the screen reader in browse mode somehow? I would find this very useful.

We are replacing some text and tspan elements with foreignObject HTML in the hope that the default HTML5 semantics therein (headings, lists) could be made available somehow, but I don't know what the 'approved' mechanism for that would be.

Currently, we just copy the text nodes from the foreign object into an aria-label, which gets announced, but is hardly ideal - since it just becomes plain text. In our case, the semantic text is rendered on-screen, but I can imagine cases where we would not want to do that.