Turkbear, I have done this and the dictionary information of the
objects in the dropped datafile were still there. In fact we counted
on Oracle to behave that way since the tablespaces in question were all
index tablespaces. We dropped the datafiles, told Oracle to recover,
it did since all data tablespace datafiles were current, then we
generated the index source from the dictionary, dropped the tablespaces
including contents, recreated them, and recreated the indexes.

We only went this route becuase we had a corrected archived redo lot
and could not forward recover past the corruption. Now days Oracle
provides the ability to skip the corruption and continue the recovery.

HTH -- Mark D Powell --