In communications messages, a date-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 the time zone, if different from Coordinated Universal Time (UTC). The order in which these elements are presented may vary. The DTG is usually placed in the header of the message. One example is "00:04 Jan 27, 2023 (UTC)"; while another example is "00:04 27 Jan 2023".
The DTG may be used as a message identifier if it is unique for each message.