+
+The characters @samp{E} and @samp{O} act as modifiers when used between
+@samp{%} and one of the letters in the table above. @samp{E} specifies
+using the current locale's ``alternative'' version of the date and time.
+In a Japanese locale, for example, @code{%Ex} might yield a date format
+based on the Japanese Emperors' reigns. @samp{E} is allowed in
+@samp{%Ec}, @samp{%EC}, @samp{%Ex}, @samp{%EX}, @samp{%Ey}, and
+@samp{%EY}.
+
+@samp{O} means to use the current locale's ``alternative''
+representation of numbers, instead of the ordinary decimal digits. This
+is allowed with most letters, all the ones that output numbers.
+
+If @var{universal} is non-@code{nil}, that means to describe the time as
+Universal Time; @code{nil} means describe it using what Emacs believes
+is the local time zone (see @code{current-time-zone}).
+
+This function uses the C library function @code{strftime} to do most of
+the work. In order to communicate with that function, it first encodes
+its argument using the coding system specified by
+@code{locale-coding-system} (@pxref{Locales}); after @code{strftime}
+returns the resulting string, @code{format-time-string} decodes the
+string using that same coding system.