I'm discovering that WORM is a world in itself. After taking forever to try to image a 470MB disc and taking forever to do it because of automatic retries on unwritten sectors, I've discovered that WORM has a SCSI2 command that's unique to it--38H, "Medium Scan" which can be used to identify groups of written or blank blocks. There are, of course, other optional WORM-specific commands, but I thought that I'd pass this one along, as it doesn't occur in any other medium type, as far as I'm aware.
--Chuck
