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.