docs: def build(self, builder):
          """Build XML by appending to builder"""
  
          params = dict(OID=self.oid, Name=self.name)
  
          if self.unit_dictionary_name:
              params["mdsol:UnitDictionaryName"] = self.unit_dictionary_name
  
          for suffix in ["A", "B", "C", "K"]:
              val = getattr(self, "constant_{0}".format(suffix.lower()))
              params["mdsol:Constant{0}".format(suffix)] = str(val)
  
          if self.standard_unit:
              params["mdsol:StandardUnit"] = "Yes"
  
          builder.start("MeasurementUnit", params)
          for child in self.symbols:
              child.build(builder)
          builder.end("MeasurementUnit")