This OCTET STRING of exactly 17 bytes, read-create, holds the MAC address, in colon- or dash-delimited text form (hence the 17-character length), of the active board in a table indexed by hwActiveMACIndex, where index 0 is the main MAC address. An admin sets or reads it to track which MAC address the currently active control board is using, relevant on chassis systems with redundant active/standby boards. For example, hwActiveMacAddress might hold a value like '00-e0-fc-12-34-56' for the active board's main interface.