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2.14.3 Continuation of unsolicited display update message

Like other types of HL7 messages, the UDM message can be continued by use of the DSC segment and MSH-14-continuation pointer. Thus if a UDM needs to be continued as three separate UDM messages, the first message would contain:

MSH      (no continuation pointer)
URD 
[URS]  
{  DSP  }  
DSC      (with continuation pointer)

The second message would contain:

MSH      (continuation pointer (to first message))
{  DSP  }
DSC      (with continuation pointer)

The last message would then contain:

MSH      (continuation pointer (to second message))
{  DSP  }
    (no DSC, since last)

Note: This scheme works equally well with non-display messages, such as the Unsolicited Update ORU message (see Chapter 7).

Since these are unsolicited messages, intervening messages (from other systems) may be sent to the receiving application while the sections of the particular message are being continued. MSH-14-continuation pointer enables the receiving system to keep track of extraneous intervening messages.

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