The value of 'hrDeviceIndex' corresponding to the first
associated conceptual row in the 'hrDeviceTable' representing
a supported and (possibly) ready 'logical' device, which has
'xcmHrDevInfoRealization' of 'logical' or 'logicalAndPhysical',
or zero, if there is no supported and subordinate 'logical'
device associated with this row (ie, this running software).