Question: Standard formatting of date/time strings

[×××××× ××××× <tombackton gmail com>]

Hi,

In Glib there's a structure GDateTime, and there's a function which
converts it into a string using a given format string, passed as a
parameter. (Personally I work with glibmm, i.e. I use Glib::DateTime)
I'd like to convert my datetime object to a string, but how do I choose
the format? I'd like to use a format knowing it's a standard common
format which will suit any locale.

But the documentation says nothing about standard formats. So I checked
how Gedit implements the inert-time plugin, and I found an array of
format strings, hard-coded. I tried to find the format Nautilus uses but
I couldn't find it in the source files...

Are there some standard formats I (and everybody else) could use?