Thanks.
I have a couple more questions.
1. Why do I need to specify a different  ADSM prefix in the new device
class?
2.  When we change our primary tape storage pool from devclass=CARTRIDGE
(which uses devtype=CARTRIDGE)  to devclass=3590 (or whatever devclass name
we come with for the new devclass)     then we have to make all primary
tape storage pool tapes read-only, right?
And when we do a restore, it will call for the old cartridge tape using
devclass=3590,  and it will still be able to read it?