Reference pg_user ?

Hello,

I need users and groups for an application and thought about
using ordinary postgres users and groups.

But I need some additional information like name, email-addres and the
like, so i tried to use something like:

test=# create table users (
test(# shortname name references pg_user,
test(# lastname varchar not null,
test(# email varchar not null
test(# );
NOTICE: CREATE TABLE will create implicit trigger(s) for FOREIGN KEY
check(s)
ERROR: Referenced relation "pg_user" is not a table
NOTICE: CREATE TABLE will create implicit trigger(s) for FOREIGN KEY
check(s)
ERROR: Referenced relation "pg_user" is not a table

Is it somehow possible to reference the system catalog with
the users ?

Thanks, Carsten

--
Dipl. Ing. Carsten Zerbst | carsten(dot)zerbst(at)atlantec-es(dot)com