[Libvirt-cim] What does NumberOfBlocks and ConsumableBlocks in the Xen_Memory class represent?

All, I am trying to understand the use of NumberOfBlocks and ConsumableBlocks in the Xen_Memory class, specifically for the Xen host. What I have noticed is that between libvirt-cim-0.4.1 and libvirt-cim-0.5.2 the values for NumberOfBlock is now different than ConsumableBlocks and much larger than the physical memory installed on the system. Is it the case that NumberOfBlocks represents the maximum possible blocks for the hardware, or some such number ConsumableBlocks is the memory that is actually installed in the system? On my system, however, NumberOfBlocks reports 16TB where /proc/meminfo reports 32Tb for VmallocTotal. In short, should I be using ConsumableBlocks to determine the total physical memory on the system? Thanks for your help. Dayne