The following is based on the example device dkb1.2.3.4.5 taken from a Digital Server 3300 (Whitebox version of an AS800).
Two letter port or class driver designator:
DR: RAID set device
DV: Floppy Drive
EW: Ethernet port (TULIP, DEC 21040)
EI: Ethernet port (Intel 82557 or 82559)
PK: SCSI port (controller)
DK: SCSI disk
MK: SCSI tape
PU: DSSI port
DU: DSSI disk
MU: DSSI tape
JK: SCSI monitor (or robot)
DQ: (E)IDE Device (disk or CD-ROM)
b-> adapter ID (one letter adapter designator)
1->Device number (SCSI unit numbers are forced to 100x Node ID)
2->Bus Node ID
3->Channel Number
4->Channel Number (used for multi-channel devices)
5->Logical Slot number
EISA: they correspond to the physical slot numbers (1-3)
PCI:
slot 5= SCSI controller on system backplane (DS3300)
slot 6= On board VGA (DS3300)
slot 7= PCI to EISA bridge chip (DS3300)
slots 11 - 14 = Correspond to Physical PCI option slots: PCI11, PCI12, PCI13 and PCI14 (64bit) (DS3300)
6->Hose number: 0 PCI_0 (32bit PCI); 1 EISA (DS3300)