HL7^® Reference Guide

MFN_M13 is the general master-file notification for simple reference files. Use it when the master file is basically a set of keys and display values, and the record can be carried in MFE-4 Primary Key Value without needing a dedicated HL7 segment such as OM1, LOC, or CDM.

It is a good fit for small lookup lists and a poor fit for records with real structure. If the receiver needs hierarchy, pricing, specimen rules, answer lists, location departments, or other multi-field behavior, use a more specific MFN event or a site-defined profile instead.

A small MFN M13 example

What workflow it represents

The sender is the system that owns a simple reference table. The receiver loads the keys and descriptions so later patient, order, billing, or reporting messages can use the same values.

MFN_M13 is intentionally plain. It is useful when the cost of a custom segment or larger profile would be higher than the value of the data being shared. That plainness is also the boundary: once the lookup value needs more than a key and text, M13 starts to creak.

How to read the structure

MSH identifies the message. MFI identifies the master file being updated and the file-level action. Each repeating MFE segment carries the record-level action, effective time, key value, and key value type.

Unlike the richer MFN messages, there is no following record segment after MFE. The key and text value live in MFE-4, so the coding system and assigning context matter.

MFK_M01 is the corresponding application acknowledgment when the sender needs to know which simple lookup rows were applied or rejected.

Implementation traps

The biggest trap is stretching M13 past its shape. If you need multiple attributes, effective pricing, nested relationships, or structured metadata, do not hide all of that in a display string.

Another trap is forgetting local ownership. A simple lookup still needs an owning application, a key format, an effective-date rule, and a delete/inactivate rule. Without those, the feed becomes a polite way to spread ambiguity.

Finally, be explicit about replace-file behavior. A full table refresh can mean "delete missing rows" in one interface and "update only the rows sent" in another. That difference should not be left to the receiver's imagination.

Reference notes

HL7 v2+ describes MFN_M13 as the general master-file notification for simple master files that contain only a key and text value, carried in MFE-4. The structure is MSH, optional SFT, required MFI, and repeating MFE.