title: Does the order of segments in HL7 V2 matter?
body: <p>I know that the order of fields and components matter, but what about the order of segments in an HL7 message?
  They all obviously have to have the MSH at the beginning, but is there anything in the HL7 guides that explicitly state that hl7 Segments must be in a particular order.
  Certainly, the documentation lists segments in a certain order when describing a message type, but isn't that just the order it was written down? Do you need to have your messages in the same order (other than the grouped items)?
  I would have thought that the PID-1 would be irrelevant if the order was set by the order in the message.</p>
  
  <p>I'm keen to hear any opinions, but I would particularly like to hear from someone that can reference some documentation that specifies this.</p>