The value of 'xcmCommsAddressIndex' corresponding to a next
associated conceptual row in the 'xcmCommsAddressTable', or zero
if this is the last associated conceptual row in a given set.
Usage: A locally administered 'directory' MAY be searched
and/or managed via use of the 'xcmCommsAddressNextIndex'
and the 'xcmCommsAddressPreviousIndex' objects referenced
from each base protocol entity (ie, stack layer).