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 } } |