A table defining the networks in a network group.
All etsysFWNetwkInNetGrpSubNetwork objects in a
etsysFWNetworkGroupName must have the same
etsysFWNetworkIPVersion and etsysFWNetworkRealm.
The implementation may choose to allow modifications to this
table only under certain SNMP contexts. The
etsysFWNetwkInNetGrpStorageType for a given SNMP context may be
readOnly, meaning the row cannot be modified or deleted. In
another SNMP context, the etsysFWNetwkInNetGrpStorageType value
could allow the row to be modified or deleted.