Georg Brandl added the comment:
%f and %z are not standardized by C89 and therefore not always
available. They fall under the clause "Additional directives may be
supported on certain platforms, but only the ones listed here have a
meaning standardized by ANSI C." which is noted for time.strfti
New submission from Riccardo Attilio Galli :
there are discrepancies in the online documentation of
strftime
in time.strftime http://docs.python.org/library/time.html
and datetime.strftime (http://docs.python.org/library/datetime.html)
In particular, seems like datetime.strftime is the one up