How to create an abstract data type (ADT) under postgresql / postquel ?

Hello,
I tried to create a new type under PostGreSQL like this :
create type point (input=int,output=int,x=int,y=int)
But I have this error :
ERROR:  TypeCreate: function pg_catalog.int4(cstring) does not exist
How can I create an abstract data type? I always have an error due to the
input or output argument.
Thanks a lot if you can help me,
Laurent

--
Laurent FALLET  -  laurent.fallet@insa-rouen.fr
Elève-ingénieur à l'INSA de Rouen  -  http://asi.insa-rouen.fr/~lfallet/