Some MicroVAXes in the 3100 series came with two SCSI busses. There are designated A and B. The SCSI id for the MicroVAX controller was typically 7; so devices could be attached with ids from 0 to 6. The naming of the devices, when VMS is booted are:
ddcn: when dd is the name of the driver controlling the device. If the device is disk, this is DK (DKDRIVER). If the device is a tape, it's MK (MKDRIVER). The 'c' in the device designation if the adapter upon which the device is located. If there are two adapters, this is either A or B. The 'n' is the device number. Unless you're looking as a dvices served from a storage controller, the sub-LUN vallues are 0. So on your MicroVAX, you see somehting like a DKA300: for a disk addressed as SCSI id 3 on the A adapter.
If you need more info, ask.
This applies exactly, thanks. Bill