A unique value used by this host system to identify this
conceptual row in the 'xcmSvcMonServiceTable'.
Usage: Conforming management stations and management agents
SHALL ensure that 'xcmSvcMonServiceIndex' is equal to
'xcmSecServiceIndex' for the same service (if the XCMI Security
MIB is also implemented).
Usage: This object SHALL be permanent (ie, preserved
across all hardware resets).