When I do a man strftime, I get:
in reply to strftime reference for Win32
The following conversion specifications are supported:
%a Replaced by the locale's abbreviated weekday
%A Replaced by the locale's full weekday name.
%b Replaced by the locale's abbreviated month
Maybe you just need to install better man pages? If you were doing a perldoc POSIX, I sympathize...
Update: To be fair, the POSIX perldoc contains the text:
Consult your system's "strftime()" manpage for details
about these and the other arguments.