Hi there,
what's wrong to use SERIAL as FK without explicit PRIMARY KEY or UNIQUE ?
qq=# create table t1( id serial);
NOTICE: CREATE TABLE will create implicit sequence "t1_id_seq" for "serial" column "t1.id"
CREATE TABLE
qq=# create table t2( id2 int4 references t1(id));
ERROR: there is no unique constraint matching given keys for referenced table "t1"
btw, Richard, I noticed this problem when looked into your example database
http://www.archonet.com/pgdocs/chap-exdb.html#EXAMPLE-TABLES
Regards, Oleg
_____________________________________________________________
Oleg Bartunov, sci.researcher, hostmaster of AstroNet,
Sternberg Astronomical Institute, Moscow University (Russia)
Internet: oleg@sai.msu.su, http://www.sai.msu.su/~megera/
phone: +007(095)939-16-83, +007(095)939-23-83