The answer to this question really depends on how you want to set it up. If you ibnotify on a device-level descriptor (opened with ibdev) for RQS, you are getting a notification that that device alone has asserted its RQS bit. If you ibnotify on a board-level descriptor (opened with ibfind) for SRQI, you can get a notification when any device asserts SRQ (which usually means that some device has asserted its RQS bit, but you have to figure out which one did).
Hope this helps.
Scott B.
GPIB
National Instruments