Documentation/date-formats.txt

DATE FORMATS
------------

The `GIT_AUTHOR_DATE`, `GIT_COMMITTER_DATE` environment variables
ifdef::git-commit[]
and the `--date` option
endif::git-commit[]
support the following date formats:

Git internal format::
	It is `<unix timestamp> <time zone offset>`, where `<unix
	timestamp>` is the number of seconds since the UNIX epoch.
	`<time zone offset>` is a positive or negative offset from UTC.
	For example CET (which is 1 hour ahead of UTC) is `+0100`.

RFC 2822::
	The standard email format as described by RFC 2822, for example
	`Thu, 07 Apr 2005 22:13:13 +0200`.

ISO 8601::
	Time and date specified by the ISO 8601 standard, for example
	`2005-04-07T22:13:13`. The parser accepts a space instead of the
	`T` character as well.
+
NOTE: In addition, the date part is accepted in the following formats:
`YYYY.MM.DD`, `MM/DD/YYYY` and `DD.MM.YYYY`.