This is an extension to nip84
A comment tag may be added to create a quote highlight. This SHOULD be rendered like a quote repost with the highlight as the quoted note.
This is to prevent the creation and multiple notes (highlight + kind 1) for a single highlight action, which looks bad in micro-blogging clients where these notes may appear in succession.
p-tag mentions MUST have a mention attribute to distinguish it from authors and editors.
r-tag urls MUST have a mention attribute to distinguish from the highlighted source url. The source url MUST have the source attribute.