folks i have one question to ask.

I am not cleared in my mind with this

CASE 1
see when the database is running in ARCHIVELOG MODE and when u want to do a Tablespace or datafile recovery - u need not shut it down because u will have the trouble opening it again with datafiles missing.
Then u take the tablespace or datafile offline with immediate option.
restore the damaged file
recover the tablespace or datafile with reover command.
then bring tablespace online.

AND WHEN
CASE 2
u afe doing Incomplete recovery , Time based , Cancel based , changed based u need to shutdown the db using shutdown abort.
restore all datafiles
startup and mount
run your recovery using appropriate statement options.
recover database unti cancel
recover database unti change scn
recover database unti time.

why is the shutdown not neccessary in first case.
can we do a tspace or datafile recoverY when the db is open AND RUNNING .

please reply.