HL7 NMQ_N01 Application Management Query

A legacy query for an application's clock, statistics, or status.
HL7 message structure NMQ_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
NMQ_N01.QRY_WITH_DETAIL
 Qry With Detail group No No
QRD
 Original-Style Query Definition Yes No
QRF
 Original style query filter No No
NMQ_N01.CLOCK_AND_STATISTICS
 Clock And Statistics group Yes Yes
NCK
 System Clock No No
NST
 Application control level statistics No No
NSC
 Application Status Change No No

NMQ_N01 asks another application for management information. The requester may want the remote clock, statistics counters, current status, or a combination of those operational data points.

This is operational HL7, not patient HL7. It belongs in monitoring, interface operations, and high-availability conversations rather than clinical document or chart workflows.

A small NMQ N01 example

MSH|^~\&|MONITOR|CITYHOSP|HL7GATEWAY|CITYHOSP|20260718122000||NMQ^N01^NMQ_N01|NMQN010001|P|2.5.1 QRD|20260718122000|R|I|NMQN010001|||1^RD|HL7GATEWAY01|STAT^Application status^L|OPS QRF|OPS|20260718000000|20260718235959 NCK|20260718122000 NST|Y|HL7GATEWAY01|APP NSC|QUERY|CPU-A|FS1|HL7GATEWAY^CITYHOSP|CITYHOSP

What systems do with it

A monitoring system or peer application sends NMQ_N01 to ask for operational status. The responder typically answers with NMR_N01, including the requested clock, statistics, and status segments.

The query can be broad or narrow. A site may query all management data, only clock synchronization, only message counters, or only current application status.

How to read the structure

MSH identifies NMQ^N01^NMQ_N01. Optional QRD and QRF provide old-style query detail. The repeating management group can include NCK, NST, and NSC as query detail or requested data types.

Implementation traps

Make sure the query scope is clear. "Status" may mean current process state, interface queue state, last-error state, hardware failover state, or all of those.

Also be careful exposing counters and infrastructure names across trust boundaries. Application management messages can reveal operational details that should stay internal.

Reference notes

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