docs: def build(self, builder):
          """Build XML by appending to builder"""
          params = dict()
  
          if self.variable_oid is not None:
              params["VariableOID"] = self.variable_oid
  
          if self.data_format is not None:
              params["DataFormat"] = self.data_format
  
          if self.folder_oid is not None:
              params["FolderOID"] = self.folder_oid
  
          if self.field_oid is not None:
              params["FieldOID"] = self.field_oid
  
          if self.form_oid is not None:
              params["FormOID"] = self.form_oid
  
          if self.static_value is not None:
              params["StaticValue"] = self.static_value
  
          if self.function is not None:
              params["Function"] = self.function.value
  
          if self.custom_function is not None:
              params["CustomFunction"] = self.custom_function
  
          if self.record_position is not None:
              params["RecordPosition"] = str(self.record_position)
  
          if self.form_repeat_number is not None:
              params["FormRepeatNumber"] = str(self.form_repeat_number)
  
          if self.folder_repeat_number is not None:
              params["FolderRepeatNumber"] = str(self.folder_repeat_number)
  
          if self.logical_record_position is not None:
              params["LogicalRecordPosition"] = self.logical_record_position.value
  
          builder.start("mdsol:CheckStep", params)
          builder.end("mdsol:CheckStep")