"Jim C. Nasby" <jim@nasby.net> writes:
> FWIW, I'm running into this trying to create a 'raw' domain that would
> automagically convert hex strings into actual binary data for storage in
> a bytea.
I think you've got 0 chance of implementing that as a domain rather than
an independent type. Without or without revisions in the casting rules,
a domain has not got its own I/O functions, and never will.
regards, tom lane