** 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



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