ALTER DIMENSION [schema .] dimension 
{ ADD 
  { level_clause
  | hierarchy_clause
  | attribute_clause
  } 
  [ADD
   { level_clause
   | hierarchy_clause
   | attribute_clause
   }
  ]...
| DROP
  { LEVEL level [ RESTRICT | CASCADE ]
  | HIERARCHY hierarchy) 
  | ATTRIBUTE level
  } 
  [DROP 
   { LEVEL level [ RESTRICT | CASCADE ]
   | HIERARCHY hierarchy) 
   | ATTRIBUTE level
   }
  ]... 
| COMPILE 
}
;