Larry Rosenman <ler(at)lerctr(dot)org> writes:
> Maybe ctid needs to be documented better?
I think it's documented about as well as OID is, actually --- see
http://www.ca.postgresql.org/users-lounge/docs/7.1/postgres/sql-syntax-columns.html
which AFAIR is the only formal documentation of any of the system
columns.
regards, tom lane