proposed FAQ entry

Earlier today I was tempted to start storing usesysid's as foreign keys
in one of my tables by doing:
SELECT usesysid FROM pg_user WHERE pg_user.usename= user;

My proposed FAQ entry is based on this mailing list post which convinced
me not to:
http://archives.postgresql.org/pgsql-novice/2005-04/msg00328.php

So the Question would be:

Q) How do I keep track of edits to a table? OR Can I use store usesysid
in my table to identify users?

A) No because usesysid values are not guaranteed to remain the same
after a restore, or upgrade. Instead store the user name as text, if
needed create your own user table and associate the user names with
integer keys.