anchor.diff:  
   undo_tablespace_clause
       : UNDO TABLESPACE tablespace_name=id_expression
  -        datafile_specification? 
  +        datafile_specification?
           extent_management_clause? tablespace_retention_clause?
       ;
   
  
positive.code:     : SCOPE IS tableview_name
      | WITH ROWID
      | (CONSTRAINT constraint_name)? references_clause constraint_state?
      ; 
  
  out_of_line_ref_constraint
      : SCOPE FOR '(' ref_col_or_attr=regular_id ')' IS tableview_name
  
negative.code:     ;
  
  alter_cluster
      : ALTER CLUSTER  cluster_name
          ( physical_attributes_clause
          | SIZE size_clause
          | allocate_extent_clause
          | deallocate_unused_clause
          | cache_or_nocache
          )+
          parallel_clause?
          ';'
      ;
  
  