The primary purpose of AliasMode is to allow aliasing at the zone apex, where
CNAME is not allowed. In AliasMode, TargetName MUST be the name of
a domain that has SVCB, AAAA, or A records. It MUST NOT be equal to
the owner name, as this would cause a loop.
From my reading, this should say that TargetName MUST be the name of a domain that has AAAA or A records, or records of the same RRTYPE as that of the source record. The intro says that
All behaviors described as applying to the SVCB RR also apply to the
HTTPS RR unless explicitly stated otherwise.
but that does not (and should not) explicitly encourage readers to alpha-substitute HTTPS for SVCB in every normative statement.
§ 2.4.1 says:
From my reading, this should say that TargetName MUST be the name of a domain that has AAAA or A records, or records of the same RRTYPE as that of the source record. The intro says that
but that does not (and should not) explicitly encourage readers to alpha-substitute HTTPS for SVCB in every normative statement.