This read-only integer object is the table index for a row in the ingress priority-mapping table, representing one priority value slot, where valid index ranges are 1 to 8 for TOS or 802.1p mode and 1 to 64 for DSCP mode depending on the port's configured priority mapping mode. An administrator uses this index to locate the specific mapping row that translates one particular incoming priority marking to a Class of Service. For example, in DSCP mode an operator would look up index values across the full 1-to-64 range to review or adjust the mapping for every possible DSCP codepoint.