Instant Archive is a backupset and yes, you can restore individual files -
however, in order to do so - you need to indicate the exact location of the
tape and the file - this is one feature <out of many> that I do not like
about the backupsets - but anyway, to further explain -

Our robot has 12 drives - if I put the tape in drive01 - /dev/rmt/0mt is the
element - therefore, I would have to let the restore know that the tape is
in this element and then proceed to tell it where the file is <ex:
c:\data\datain.txt> - otherwise, you can restore from the server, in which
case, you end up restoring the whole backupset.

What would have been nice, is if they implemented this feature with some of
the features of regular archiving - where you can search for the process -
have a good tracking system of the tapes, and they could have implemented it
to allow DRM to handle the offsite storage - just as it is done in the
copypools. :0)