This scans a specification and pulls out all the "MUST", "REQUIRED", "SHALL", "SHOULD", "RECOMMENDED", "MAY", "OPTIONAL" terms (and also the "* NOT" terms).
This works pretty well for EPUB and Audiobook specs. Generally, if the document is a single page and uses the section element, it should do well.
If the spec does not use the section element, then the links aren't really specific to the subsection, mostly because I don't really have time to make this a universal spec analyzer. PRs though are welcome :)