anchor.diff:  `Expression` for this purpose.
   
   
  -*Charset*
  +==== Charset
   
   As of *Camel 2.14.1*, both `marshal and unmarshal` evaluate the charset
   provided in the field `MSH-18`. If this field is empty, by default the
  
positive.code: object:
  
  [source,java]
  ------------------------------------------------------------------------
    from("direct:hl7in").marshal().hl7().to("jms:queue:hl7out");
    from("jms:queue:hl7out").unmarshal().hl7().to("patientLookupService");
  ------------------------------------------------------------------------
  
  ### Message Headers
  
  The unmarshal operation adds these fields from the MSH segment as
  headers on the Camel message:
  
  [width="100%",cols="10%,10%,80%",options="header",]
  |=======================================================================
  |Key |MSH field |Example
  
  |`CamelHL7SendingApplication` |`MSH-3` |`MYSERVER`
  
negative.code: type in advance, you can be more type-safe:
  
  [source,java]
  ----
  QRY_A19 msg = exchange.getIn().getBody(QRY_A19.class);
  String patientId = msg.getQRD().getWhoSubjectFilter(0).getIDNumber().getValue();
  ----
  
  === HL7 DataFormat
  
  The <<hl7-dataformat,HL7>> component ships with a HL7 data format that can
  be used to marshal or unmarshal HL7 model objects.
  