Within a product, there may be several identifiers of such firmware, boot proms, kernel versions, flash versions, etc. This field (and the 3 that follow) are used to hold the identification of these items. These values must be entered into the board at the time of manufacturing. Unused fields are reported as null values. These fields are available to the network manager for applications that keep track of the firmware related identification. There is no specification of the internal format of firmware version identifiers.