This managed object returns the next available DDS ID that
MAY be used for DDS creation for this iSNS Server instance.
The user should read and use the value of cIsnsNextIdxDds
before performing a cIsnsDdsTable row creation. The
cIsnsNextIdxDds value returned MAY be used as the index
value when creating a new row in the cIsnsDdsTable. Use
of this managed object reduces the chance for an index
conflict.