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