HL7 v2 MSH-7 (Date/Time of Message): Format, Values, and Testing Notes
MSH-7 looks like a simple timestamp, but source systems vary in both the precision they send and whether they include a timezone offset at all — and any logic that orders or de-duplicates messages by this field inherits every one of those inconsistencies.
MSH-7 is the seventh field of the MSH segment — a timestamp recording when the sending system created the message, in YYYYMMDDHHMMSS format with an optional timezone offset.
What this field contains
Example
The 7th field, 20260727143000, records the message as created on July 27, 2026 at 2:30:00 PM. Synthetic message — not a real transmission.
Where this trips people up
Interfaces that compare MSH-7 across messages from different source systems to determine ordering or detect duplicates often assume every feed reports in the same timezone with the same precision — an assumption that holds fine within a single system and breaks the moment a second source system, running on a different clock convention, gets connected to the same interface engine.