Only tangentially related to the main subject, but the post ends with:

> Extensions to the predefined set of link types may be registered on the microformats page for existing rel values.

Please don't. WHATWG's tendency to self-anoint and all its idiosyncrasies notwithstanding, the IANA maintains the link relation registry[1]. Use the procedure prescribed in the RFCs.

1. <https://www.iana.org/assignments/link-relations/link-relatio...>