Replace RFC 6966 with RFC 7766 at https://ednscomp.isc.org/ednscomp/
https://ednscomp.isc.org/ednscomp/1d4f143106 says
EDNS - over TCP Response (edns@512tcp)
dig +vc +nocookie +norec +noad +edns +dnssec +bufsize=512 dnskey zone @server
expect: NOERROR
expect: OPT record with version set to 0
See RFC5966 and See RFC6891
Since RFC5966 is obsoleted by RFC 7766, the latter RFC shall be referenced.