(B)0[mduplicates-clause = qqq> [4mDUPLICATES[m ARE qqwqqqqqqq>qwqq> [4mALLOWED[m qq> mq> [4mNOT[m qqj A clause specifying whether each value of the index must be unique. If you try to store the same value twice in an indexed field defined as DUPLICATES NOT ALLOWED, Oracle Rdb returns an error message and does not store or modify the record.