Martijn van Oosterhout developed "tagged types" back in 2005, looks like it went nowhere. You can search for it, it was pretty interesting.
-- Álvaro Herrera http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services -- Sent via pgsql-general mailing list (pgsql-general@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
