In communications messages, adate-time group (DTG) is a set of characters, usually in a prescribed format, used to express the year, the month, the day of the month, the hour of the day, the minute of the hour, and thetime zone, if different fromCoordinated Universal Time (UTC).[citation needed] The order in which these elements are presented may vary. The DTG is usually placed in theheader of the message. One example is "18:36 Oct 14, 2025 (UTC)"; while another example is "18:36 14 Oct 2025".
The DTG may indicate either thedate and time a message was dispatched by a transmitting station or the date and time it was handed into atransmissionfacility by auser or originator for dispatch.
The DTG may be used as a messageidentifier if it is unique for each message.
A form of DTG is used in theUS military'sDefense Message System (a form ofAutomated Message Handling System). In US military messages and communications (e.g., on maps showing troop movements) the format isDD HHMM (SS) Z MON YY. Although occasionally seen with spaces, it can also be written as a single string of characters. Three different formats can be found:
Z references the military identifier of time zone:
Example 1:051100Z represents the 5th day of the current month 11:00 (UTC).
Example 2:091630Tjul11 represents 9 July 2011 4:30 pm (MST).
Example 3:14183642ZOct25 represents the current time of refresh: (Oct) 14 18:36:42, Oct 2025 (UTC).
This article incorporatespublic domain material from"date-time group (DTG)".Federal Standard 1037C.General Services Administration. Archived fromthe original on 22 January 2022.