CALL routine [ pass-mech ] [ ( [ actual-param ],... ) ]

        routine:  { sub-name              }
                  { any callable routine  }

        pass-mech:  { BY REF   }
                    { BY VALUE }
                    { BY DESC  }

        actual-param:  { exp                              }
                       { array ( [,]... ) } [ pass-mech ] }