MODIFY SUBPARTITION subpartition 
{ { { allocate_extent_clause | deallocate_unused_clause }
  | { LOB LOB_item) | (VARRAY varray } modify_LOB_storage_parameters 
    [ LOB LOB_item) | (VARRAY varray } modify_LOB_storage_parameters]...
  }
| [REBUILD] UNUSABLE LOCAL INDEXES
}

For information on the symbols and conventions of Backus-Naur Form (BNF) syntax, see Appendix A.