** What is this ** This page is intended to evolve into a collection of `clock format` strings for producing the different formats used in different [RFC]s. ** Email dates ** [LEG] https://tools.ietf.org/html/rfc5322#section-3.3%|%RFC5322, 3.3 Date and Time Specification%|% There are multiple ways for formatting date and time in the Internet Message Format. The current (2018) canonical way of doing it seems to be the following: ====== clock format [clock seconds] -format "%d %b %Y %T %z" ====== If you want omit information about the current timezone the UTC timezone with a minus sign has to be used. This might be the case, if you have a (worldwide distributed) webmail system where users from timezones other then the server send Email. ====== clock format [clock seconds] -format "%d %b %Y %T -0000" -timezone GMT ====== ** http dates ** [LEG] https://tools.ietf.org/html/rfc7231#section-7.1.1.1%|%RFC7231, 7.1.1.1Date/Time Formats%|% Date/time in http headers shall be formatted in "Internet Message Format" - "IMF-fixdate", RFC7231 references RFC5322, but restricts the format in the following way: Date/time must always be in UTC, not in local time and the timezone indicator must be 'GMT'. ====== clock format [clock seconds] -format "%a, %d %b %Y %T %Z" -timezone GMT ====== ** ISO8601/RFC3339 ** [LEG] https://en.wikipedia.org/wiki/ISO_8601%|%Wikipedia on ISO8601%|%, https://tools.ietf.org/html/rfc3339#section-5.6%|%RFC3339, 5.6. Internet Date/Time Format%|% UTC: ====== clock format [clock seconds] -format %Y-%m-%dT%H:%M:%SZ -timezone GMT ====== Todo: Add format with time zone notation <<categories>>Date and Time | Example