This document fills a gap created by RFC 6275 by creating a necessary IANA registry.  The document is well written and ready to go, with no security implications that I can imagine.

I read Al Morton's OpsDir review.  Commenting on that:
- I think the document can go ahead with or without the changes that Al suggests, but...
- I agree that it'd be useful to show the reserved bits in the registry table, except that I'd give the reference for it as RFC 4861, not 6275.
- The text in Section 4 already does say what the registration policy is, and I don't think "or IESG Approval" should be added.
- I don't think it's necessary to add "updates 6275", though I wouldn't object to it.
- I agree that adding section references would be nice.  I found the fields easily by searching on their names, but I'm a general fan of using section references to make things clearer to readers.

-- 
Barry