keep and drop options are specified in the datastep or proc , the difference is when we write options in datastep it will be permanent to the dataset but where as in proc , it will not be permanent and stays affect fot that particular session only.
Message was edited by: reena
It is very much possible to affect a SAS permanent library when using the DROP= and/or KEEP= parameter, if you have WRITE authority to your SAS permanent database. This capability will be dependent on the user's session and their authority permissions. For example, consider this code:
PROC SORT DATA=PERMIN.MASTER OUT=PERMOUT.MASTER (DROP=X Y Z);
If the OUT= (here PERMOUT) is a permanent library, not just for your session, the result is not going to be just for your session.