table name restiction

PostgreSQL users,
    What are the restrictions on naming tables or columns in tables other
than uniqueness (assuming ascii characters)?  For instance, are names
case sensitive.  What special characters can be used     (`_`,`-`,` `).
  I looked at the docs in the tutorial part in the beginning and in the
description of CREATE TABLE but could not find naming restriction info.
  Could someone point me in the right direction?

Thanks,

Dale