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2.11.1 HL7 abstract message syntax example

The schematic form for this hypothetical exchange of messages is shown in Figure 2-5:

Figure 2-5. Hypothetical schematic message

Trigger Event: WIDGET REPORT IS REQUESTED
WRQ            Widget Request           Chapter
MSH            Message Header              2
WID            Widget ID                   XX
WRP            Widget Report            Chapter
MSH            Message Header              2
MSA            Message acknowledgment      2
{ WDN          Widget Description          XX
  WPN          Widget Portion              XX
  { [WPD] }    Widget Portion Detail       XX
}

The WID, WDN, WPN, and WPD segments would be defined by the widget committee in the widget chapter, as designated by the Arabic numeral XX in the right column. The MSH and MSA segments, although included in the widget messages, are defined in another chapter. They are incorporated by reference into the widget chapter by the chapter number XX.

On the other hand, the widget committee might decide that the WPN and WPD segments should appear in pairs, but the pairs are optional and can repeat. Then the schematic for the WRP message would be as shown in Figure 2-6.

Figure 2-6. WPN and WPD segments in pairs

WRP            Widget Report               Chapter
MSH            Message Header                 2
MSA            Message acknowledgment         XX
{ WDN          Widget Description             XX
  [ { WPN      Widget Portion                 XX
      WPD      Widget Portion Detail          XX
   } ]
}

If the widget committee determined that at least one pair of WPN and WPD segments must follow a WDN, then the notation would be as shown in Figure 2-7.

Figure 2-7. At least one pair of WPN and WPD

WRP            Widget Report               Chapter
MSH            Message Header                 2
MSA            Message acknowledgment         XX
{ WDN          Widget Description             XX
  {  WPN       Widget Portion                 XX
     WPD       Widget Portion Detail          XX
  }
} 

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