I was pondering title (with lang) and https://w3c.github.io/html-aam/#el-title struck me as a little bit odd, also in light of #571 / w3c/aria#2504.

The title element has "not mapped" for all platforms yet the comment says it "provides the accessible name for its document".

Obviously, title is mapped somewhere to be useful. Could we say more about that here? Even if it's not testable, it seems like useful information in the spec.