RFC 822: Date and Time Specification

The syntax and semantics for the dates and times used in RFC 822 messages is defined in this section. For example, the days of the week and months of the year are enumerated, and the time is defined as:

time = hour zone ; ANSI and Military

hour = 2DIGIT ":" 2DIGIT [":" 2DIGIT] ; 00:00:00 - 23:59:59

Time zones are also specified, for example:

zone = "UT" / "GMT"  
         /  "EST" / "EDT"