Zero vs. Null quota

This is somewhat an academic question(s) -

(a) Is there any difference practically between having a null quota, and
having a zero quota? Take two users, one has in "select * from user_ts_quotas" has nothing -- no quotas defined. The other has a set of quotas listed as zero.

I've noticed that the errors are different if you try to do a CREATE TABLE, for example. If there is a ZERO quota, you get:

ORA-01536: space quota exceeded for tablespace 'BLAH'

If there is no quota defined:

ORA-01950: no privileges on tablespace 'BLAH'

(b) The follow-up is -- is there any way to "drop" a quota setting? I.e.,
instead of having it as zero, have it not exist at all? Or must you go back down to zero after any quota has been set?

This is Oracle 8.0.5.1.1 on Digital Unix 4.x.

-Rick

+--------------------------------------------------------------------------+
|                 Rick Osterberg   osterber_at_fas.harvard.edu                |
|         Database Applications Specialist     FAS Computer Services       |
+--------------------------------------------------------------------------+