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

Time zone

A time zone is a region on Earth that has a uniform standard time for legal, commercial, and social purposes. In order for the same clock time to always correspond to the same portion of the day as the Earth rotates , different places on the Earth need to have different clock times...

, if different from Coordinated Universal Time

Coordinated Universal Time

Coordinated Universal Time is the primary time standard by which the world regulates clocks and time. It is one of several closely related successors to Greenwich Mean Time. Computer servers, online services and other entities that rely on having a universally accepted time use UTC for that purpose...

 (UTC). The order may vary, for example, "21:52 Feb 20, 2003 (UTC)" .

In military messages and communications (e.g. on maps showing troop movements) the format is DDHHMMZ Mon YY, so for instance, "271545Z FEB 08" represents 15:45 Zulu time (which is to say UTC) on the 27th of February, 2008.

Note 1: The DTG is usually placed in the header

Header (information technology)

In information technology, header refers to supplemental data placed at the beginning of a block of data being stored or transmitted. In data transmission, the data following the header are sometimes called the payload or body....

 of the message.

Note 2: The DTG may be used as a message identifier

Identifier

An identifier is a name that identifies either a unique object or a unique class of objects, where the "object" or class may be an idea, physical [countable] object , or physical [noncountable] substance...

 if it is unique for each message.

Note 3: The DTG may indicate either the date

Calendar date

A date in a calendar is a reference to a particular day represented within a calendar system. The calendar date allows the specific day to be identified. The number of days between two dates may be calculated. For example, "24 " is ten days after "14 " in the Gregorian calendar. The date of a...

 and time a message was dispatched by a transmitting station or the date and time it was handed into a transmission

Transmission (telecommunications)

Transmission, in telecommunications, is the process of sending, propagating and receiving an analogue or digital information signal over a physical point-to-point or point-to-multipoint transmission medium, either wired, optical fiber or wireless...

 facility by a user

User (telecommunications)

In telecommunications, a user is a person, organization, or other entity that employs the services provided by a telecommunication system, or by an information processing system, for transfer of information....

 or originator for dispatch.
See also Calendar date

Calendar date

A date in a calendar is a reference to a particular day represented within a calendar system. The calendar date allows the specific day to be identified. The number of days between two dates may be calculated. For example, "24 " is ten days after "14 " in the Gregorian calendar. The date of a...

, ISO 8601

ISO 8601

ISO 8601 Data elements and interchange formats – Information interchange – Representation of dates and times is an international standard covering the exchange of date and time-related data. It was issued by the International Organization for Standardization and was first published in 1988...

 in Internet standard

Internet standard

In computer network engineering, an Internet Standard is a normative specification of a technology or methodology applicable to the Internet. Internet Standards are created and published by the Internet Engineering Task Force .-Overview:...

s.