Health Level 7

The environment that I'm working in involves HL7 messaging. That is "Health Level 7".

You can learn more about this protocol at HL7.org

Messages are broken into segments and field types.

A segment such as a PID (Patient Identifier) is delineated by a Chr 127. Within each segment are a number of fields. These are delinated by | characters. It is common to have many blank segments, but some can be mandatory based on whatever the system specs say.

So this is what an HL7 message looks like:

MSH|^~\&||STO|||200810021308||ADT^A03|PACS-ADT.1.7960|D|2.2|||AL|NE|||||||EVN|A03|200810021308|||ISBURC|200810021307||
PID|1||H000072|H73|ELF^EIGHT^^^^||19580426|F|^^^^^||^^^^|||||||AA000161/08|
||||||||||||||||||||PV1|1|I|1SRG^342^04|EL|||WILM^WILKS^M.^^^DR.^|||GS|||||||
WILM^WILKS^M.^^^DR.^|IN||U||||||||||||||||H|||STO||DIS|||200809051220|
200810021307||||||||PV2||SP||||||||||||||||||||||||||||||||||||||||||||||AL1|1|MA|
OEALL^EGGS, FLOUR^OE||||AL1|2|MA|OEALL1^YEAST, COCONUT, JAM^OE||||AL1|3|MA|OEALL2^PENICILLIN^OE||||

You'll see the CHR(127) or Hex 7F as . Some of the segments contained in this message are MSH (Message header), PV1 (Patient Visit Segment 1) etc. etc.

In the MSH segment field 8 (MSH8) you'll see the message type ADT^03. This is a patient discharge message. It can be further broken down as MSH8.1 ADT and MSH8.2 A03.

That's a nutshell if you want to learn more about HL7 I'd suggest Google, or ask in a comment and I'll try and help you out.