In a message, a set of characters, usually in a prescribed format, used to express the day of the month, the hour of the day, the minute of the hour, the time zone, and the year. Note 1: The DTG is usually placed in the header of the message. Note 2: The DTG may be used as a message identifier if it is unique for each message. Note 3: 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.