HL7 NMR_N01 Application Management Response

The response that reports an application's clock, counters, and current status.
HL7 message structure NMR_N01 groups and segments from HL7 v2.5.1 Hide structure

These are the generated groups and segments for the version selected at the top of the page. The article explains the workflow, and this panel follows the chosen HL7 version.

Message Structure

SegmentNameRequiredRepeatable
MSH
 Message Header Yes No
SFT
 Software Segment No Yes
MSA
 Message Acknowledgment Yes No
ERR
 Error No Yes
QRD
 Original-Style Query Definition No No
NMR_N01.CLOCK_AND_STATS_WITH_NOTES_ALT
 Clock And Stats With Notes Alt group Yes Yes
NCK
 System Clock No No
NTE
 Notes and Comments No Yes
NST
 Application control level statistics No No
NTE
 Notes and Comments No Yes
NSC
 Application Status Change No No
NTE
 Notes and Comments No Yes

NMR_N01 is the response side of the application management query workflow. It reports clock data, application statistics, status changes, and notes back to the requester.

In practice this is monitoring traffic. A receiver may use it to confirm that an interface application is alive, its clock is sane, and its message counters or status values are within expected ranges.

A small NMR N01 example

MSH|^~\&|HL7GATEWAY|CITYHOSP|MONITOR|CITYHOSP|20260718122005||NMR^N01^NMR_N01|NMRN010001|P|2.5.1 MSA|AA|NMQN010001 QRD|20260718122000|R|I|NMQN010001|||1^RD|HL7GATEWAY01|STAT^Application status^L|OPS NCK|20260718122005 NTE|1||Clock source synchronized to hospital NTP. NST|Y|HL7GATEWAY01|APP|20260718000000|20260718122000|120000|118900|4321|4310|0|0|1 NTE|2||No application-level protocol errors above threshold. NSC|UP|CPU-A|FS1|HL7GATEWAY^CITYHOSP|CITYHOSP NTE|3||Gateway is running normally.

What systems do with it

The responder receives NMQ_N01 and returns NMR_N01 with management data. MSA acknowledges the original query, and optional ERR can report problems.

Operations systems use the payload to update health dashboards, raise alerts, or reconcile message counts. Because the message can include notes, it can also carry human-readable context for maintenance windows or known degraded states.

How to read the structure

MSH identifies NMR^N01^NMR_N01. MSA links the response to the original query. Optional QRD can echo query detail. The repeating management group can include NCK, NST, and NSC, each with optional NTE notes.

Implementation traps

Do not overreact to a single counter. Statistics fields often need site-specific baselines before they are operationally meaningful.

Also normalize clocks before alerting on timing. If one application reports its own local time and another expects UTC or hospital local time, stale-data alerts can fire for the wrong reason.

Reference notes

HL7 Chapter 14 application management describes NMQ/NMR as the application management query and response pair. See the HL7 v2.5 event page for N01 and the HL7 v2.4 application management chapter.