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 "13:11 Jun 18, 2021 (UTC)"; while another example is "13:11 18 Jun 2021".
The DTG may be used as a message identifier if it is unique for each message.
Military Date Time Group
A form of DTG is used in the US Military's message traffic (a form of Automated Message Handling System). In US military messages and communications (e.g., on maps showing troop movements) the format is DD 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:
- DDHHMMSSZmmmYY - Full time (used for software timestamps)
- DDHHMMZmmmYY - shortened time (used e.g. for timestamps manually written)
- DDHHMMZ - short time (e.g. used for planing)
Z references the military identifier of time zone:
- UTC-12: Y (e.g., Fiji)
- UTC-11: X (American Samoa)
- UTC-10: W (Honolulu, HI)
- UTC-9: V (Juneau, AK)
- UTC-8: U (PST, Los Angeles, CA)
- UTC-7: T (MST, Denver, CO)
- UTC-6: S (CST, Dallas, TX)
- UTC-5: R (EST, New York, NY)
- UTC-4: Q (Halifax, Nova Scotia)
- UTC-3: P (Buenos Aires, Argentina)
- UTC-2: O (Godthab, Greenland)
- UTC-1: N (Azores)
- UTC+-0: Z (Zulu time)
- UTC+1: A (France)
- UTC+2: B (Athens, Greece)
- UTC+3: C (Arab Standard Time, Iraq, Bahrain, Kuwait, Saudi Arabia, Yemen, Qatar)
- UTC+4: D (Used for Moscow, Russia, and Afghanistan, however, Afghanistan is technically +4:30 from UTC)
- UTC+5: E (Pakistan, Kazakhstan, Tajikistan, Uzbekistan, and Turkmenistan)
- UTC+6: F (Bangladesh)
- UTC+7: G (Thailand)
- UTC+8: H (Beijing, China)
- UTC+9: I (Tokyo, Australia)
- UTC+10: K (Brisbane, Australia)
- UTC+11: L (Sydney, Australia)
- UTC+12: M (Wellington, New Zealand)
Example 1: 051100Z represents the 5th day of the current month 11:00 (UTC).
Example 2: 091630Tjul11 represents 09th July 2011 4:30 pm (MST).
Example 3: 18131106ZJun21 represents the current time of refresh: (Jun) 18 13:11:06, Jun 2021 (UTC).
- MIL-STD-2500A 12 October 1994
- TM 20-205, the Dictionary of United States Army Terms (1944)
- ACP 121(I) p 3–7