Under privileges for named row types
For named row types, you can grant or revoke the Under privilege, which controls whether users can assign a named row type as the supertype of another named row type in an inheritance hierarchy. The Under privilege is granted to PUBLIC automatically when a named row type is created (except in ANSI-compliant databases). In an ANSI-compliant database, the Under privilege on a named row type is granted to the owner of the type.
REVOKE UNDER ON person_t
FROM PUBLIC;
GRANT UNDER ON person_t
TO howie, jhana, alison
For information about how to use the UNDER clause to create named row types in an inheritance hierarchy, see Type inheritance.