IBM RS/6000 - Manual (Page 125)

6.1.2 Device Location Codes
Location Codes are defined slightly differently depending on the type of device they
are used for, non-SCSI or SCSI.
For planars, cards and non-SCSI devices, the Location Code is defined as:
AB-CD-EF-GH
For SCSI devices, the Location Code is defined as:
AB-CD-EF-G,H
While AB-CD-EF have the same meaning for both non-SCSI and SCSI devices, the
last two letters identify different codes.
AB identifies a bus type, and it can assume the following values:
00 for resources attached to the processor bus, such as system planar,
processor, memory, L2 cache, and primary PCI bus.
01 for resources attached to ISA buses, such as diskette drive, mouse adapter,
mouse, and keyboard.
04 for resources attached to PCI buses, such as ISA bus, SCSI controller,
CD-ROM drive, hard disks, and graphics adapter.
CD identifies a slot or adapter number.
The possible values for CD depend on the adapter or card. For pluggable
adapters or cards, this will be a two-digit slot number in the range from 01 to
99. In the case of ISA adapters, these numbers will not actually correspond to
the physical slot number. They will depend on the order in which the ISA cards
are defined or configured.
For integrated adapters, the first character in CD will be a letter in the range
from A to Z. The letter is based on the order that the integrated adapters are
defined in residual data and ensures unique Location Codes for the integrated
adapters. The second character, D, will be set to 0.
Any adapter or card is defined only with AB-CD.
EF is the connector identifier.
On adapters with multiple connectors, it is used to identify the adapter
connector that a resource is attached to.
GH for non-SCSI devices is a port identifier, address, DIMM, devices or a Field
Replaceable Unit (FRU). It has several meanings, depending upon the resource
type.
G,H for SCSI devices defines the following:
G defines the control-unit address of the device.
H defines the logical-unit address of the device.
The following list shows an example of PCI-based RS/6000 systems' location
codes.
Chapter 6. Adapter and Device Configuration on PCI-Based RS/6000 Servers 101