This read-only object is the integer index uniquely identifying this BITS port within its card, forming part of a composite key together with neIndex, shelfIndex, slotIndex, and bits8PortGroupIndex. Admins and management tools use this precise addressing to pinpoint exactly which BITS timing port, out of potentially many across the network element, a given alarm or configuration row refers to. For example, a monitoring system uses bits8PortGroupIfIndex alongside the shelf and slot indices to identify exactly which BITS port on which card raised a timing alarm.