returns opaque

    Hi :

       I found the following definition


      CREATE FUNCTION check_primary_key ()
        RETURNS opaque
                              ^^^^^^^
        AS '/home/postgres/postgresql-6.3.2/contrib/spi/refint.so'
        LANGUAGE 'c'
;


        and I didn't know what's the meaning of  opaque. Any suggestion
or definition ???????????

    Bye...


---------------------------------
    Paulina Canas Urrutia
    U. Tecnica Federico Santa Maria, Chile
    paulina@labsd.inf.utfsm.cl