Idoc Segement definition not released " E101COD_S_REP_CONTRACT_DATA " ??

Segement definition not released " E101COD_S_REP_CONTRACT_DATA " & need to extend the Idoc "E101COD_S_REP_CONTRACT_DATA" Contract Replication Data .but Idoc is Released "E101COD_S_REP_CONTRACT_DATA" so how to use not released segments in Extended Idoc ? please suggest