>I've not been keeping up with the IETF; is there a document that >describes what looks like a de facto standard of using _pname labels >with TXT RRs that is being followed by at least DMARC and DANE in >*._tcp.example.com, *._smimecert.example.com, and _dmarc.example.com No, but Dave Crocker is working on one. >Is SRV the precedent being followed? Yes.