HL7^® Reference Guide

MFK_M01 acknowledges a master-file notification such as MFN_M01 or one of the more specific MFN events. It can acknowledge the message as a whole and, when needed, report record-level status for individual master-file entries.

This is especially important for catalog feeds. A receiver might accept the message, reject one record because of a duplicate key, and apply the rest. If your integration only reads MSA, you may miss the actual catalog problem.

A small MFK M01 example

What workflow it represents

The receiver sends MFK after it processes or queues the master-file update. The sender uses it to decide whether to retry, investigate, or mark the catalog feed as applied.

In enhanced acknowledgment mode, MFK is the application-level response. In original mode, the choreography is simpler, but the same practical rule applies: look for the record-level status when the feed can contain more than one entry.

How to read the structure

MSH identifies the acknowledgment message. MSA points back to the original message control ID. ERR can repeat when the receiver needs to explain failures.

MFI echoes the master file context. MFA carries record-level acknowledgment details and ties back to the corresponding MFE primary key.

Implementation traps

Do not stop at MSA-1. A message-level accept does not guarantee that every catalog record was applied.

Also log the primary key from MFA. When a nightly master-file feed updates hundreds of records, "one record failed" is not an actionable error unless you can identify the record.

Reference notes

HL7 v2+ master-file material describes MFK as the application acknowledgment for master-file notifications and states that MFA carries acknowledgment information for the corresponding MFE entry.