create/alter user extension syntax

I tried the following:

{CREATE|ALTER} USER username
[ WITH ID/UID/<whatever> number ]
[ WITH PASSWORD password ]
[ etc. as usual ]

which gives shift/reduce conflicts, even if I make PASSWORD and
ID/whatever a pure keyword (WITH is already one). So that won't work.

I am currently basing my "experiments" on CREATE USER name [ SYSID nr ] [
WITH PASSWORD ... ] ... which allows SYSID to be a ColId. Any better (and
working) syntax suggestions are welcome.

(Also, the idea would be to reuse "SYSID" for a CREATE GROUP (any day now
;) statement, so no UID.)

-- 
Peter Eisentraut                  Sernanders väg 10:115
peter_e@gmx.net                   75262 Uppsala
http://yi.org/peter-e/            Sweden