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
  } ;