Intel ITANIUM ARCHITECTURE - SOFTWARE DEVELOPERS MANUAL VOLUME 1 REV 2.3 Manual page 681

PAL_MC_HW_TRACKING
The convention for the levels in the hw_track field is such that the least significant bit in
the field represents the lowest level of the structures hierarchy. For example, bit 0 of
the ICT field represents the first level instruction cache.
Volume 2, Part 1: Processor Abstraction Layer 2:433