DEFINE TYPE WellKnownPortType 
  ( value     : PortNumberType,
    min       : PortNumberType  STATIC :=     0,
    max       : PortNumberType  STATIC :=  1023,
    default   : PortNumberType  STATIC :=    80,
    units     : PortNumberType  STATIC := "PortNumber"
  ) AS
  PortNumberType
  ALLOWING NONULL
  WITH CONSTRAINTS
    ( VALUE     = default,
      MIN       = min,
      MAX       = max,
      DEFAULT   = default,
      UNITS     = units
    );

CREATE httpPortNumber = NEW WellKnownPortType ( value = 80 );