Indicating the shared SPAN capacity type.
'none' means the capacity is not shared out of
crcSpanSharedSource or crcSpanSharedDestination.
'source' means the capacity is counted against
crcSpanSharedSource. The sum of crcSpanUsedSession for all
entries with crcSpanCapacityShared being 'source' shall not
exceed crcSpanSharedSource.
'destination' means the capacity is counted against
crcSpanSharedDestination. The sum of crcSpanUsedSession
for all entries with crcSpanCapacityShared being
'destination' shall not exceed crcSpanSharedDestination.