Date-time group

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 "21:47 Apr 20, 2022 (UTC)"; while another example is "21:47 20 Apr 2022".

The DTG may indicate either the date and time a message was dispatched by a transmitting station or the date and time it was handed into a transmission facility by a user or originator for dispatch.

The DTG may be used as a message identifier if it is unique for each message.

Military Date Time Group
See also: List of military time zones

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 planning)


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, Japan)
  • UTC+10: K (Brisbane, Australia)
  • UTC+11: L (Sydney, Australia)
  • UTC+12: M (Wellington, New Zealand)

Examples

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: 20214722ZApr22 represents the current time of refresh: (Apr) 20 21:47:22, Apr 2022 (UTC).

“Zulu time” does not mean “local time” unless a Zulu time zone is specified. Earth rotates in 24 hours, thus there are 24 hours in a day. English Alphabet has 25 characters; without J, there are 24 characters like 24 hours. Zulu [Z]– is a synonym for Coordinated Universal Time (UTC); and formerly a synonym for Greenwich Mean Time (GMT).[1]

Sources

See also

References
  • TM 20-205, the Dictionary of United States Army Terms (1944)
  • ACP 121(I) p 3–7
  1. Egeland PhD, Dr Knut Normann, et al (2021: p. 3).  “Military Date Time Group - MIL DTG DDHHMMSSZmmmYY”, archived in Military Academy, private Knights University (Ko’G).

 This article incorporates public domain material from the General Services Administration document: "Federal Standard 1037C".

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