{ {ADD add_column_options
  | MODIFY modify_column_options
  | drop_column_clause
  }
    [ ADD add_column_options
    | MODIFY modify_column_options
    | drop_column_clause
    ]...
| modify_collection_retrieval [modify_collection_retrieval]...
}

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