RFC Errata
RFC 5322, "Internet Message Format", October 2008
Note: This RFC has been updated by RFC 6854
Source of RFC: IETF - NON WORKING GROUPArea Assignment: app
Errata ID: 2726
Status: Held for Document Update
Type: Editorial
Publication Format(s) : TEXT
Reported By: Tony Finch
Date Reported: 2011-02-21
Held for Document Update by: Pete Resnick
Section 3.3 says:
The zone specifies the offset from Coordinated Universal Time (UTC, formerly referred to as "Greenwich Mean Time") that the date and time-of-day represent. The "+" or "-" indicates whether the time-of- day is ahead of (i.e., east of) or behind (i.e., west of) Universal Time. The first two digits indicate the number of hours difference from Universal Time, and the last two digits indicate the number of additional minutes difference from Universal Time. (Hence, +hhmm means +(hh * 60 + mm) minutes, and -hhmm means -(hh * 60 + mm) minutes). The form "+0000" SHOULD be used to indicate a time zone at Universal Time. Though "-0000" also indicates Universal Time, it is used to indicate that the time was generated on a system that may be in a local time zone other than Universal Time and that the date-time contains no information about the local time zone.
It should say:
The zone specifies the offset from Coordinated Universal Time (UTC) that the date and time-of-day represent. The "+" or "-" indicates whether the time-of- day is ahead of (i.e., east of) or behind (i.e., west of) UTC. The first two digits indicate the number of hours difference from UTC, and the last two digits indicate the number of additional minutes difference from UTC. (Hence, +hhmm means +(hh * 60 + mm) minutes, and -hhmm means -(hh * 60 + mm) minutes). The form "+0000" SHOULD be used to indicate a time zone at UTC. Though "-0000" also indicates UTC, it is used to indicate that the time was generated on a system that may be in a local time zone other than UTC and that the date-time contains no information about the local time zone.
Notes:
It is not correct to say that UTC was formerly referred to as GMT. I think this was an editorial mistake: RFC 822 did not use the term UTC and said "Universal Time (formerly called Greenwich Mean Time)" which is reasonably correct for UT without a suffix.
For the purposes of RFC 5322 and for consistency with RFC 3339 and ISO 8601 I think it is best to refer to UTC throughout - though see the next erratum for notes on the obsolete syntax.