@table @code
@item E
-Use the locale's alternate representation for date and time. This
+Use the locale's alternative representation for date and time. This
modifier applies to the @code{%c}, @code{%C}, @code{%x}, @code{%X},
@code{%y} and @code{%Y} format specifiers. In a Japanese locale, for
example, @code{%Ex} might yield a date format based on the Japanese
@item O
With all format specifiers that produce numbers: use the locale's
-alternate numeric symbols.
+alternative numeric symbols.
With @code{%B}, @code{%b}, and @code{%h}: use the grammatical form for
month names that is appropriate when the month is named by itself,
part of a complete date. This is a GNU extension.
@end table
-If the format supports the modifier but no alternate representation
+If the format supports the modifier but no alternative representation
is available, it is ignored.
The conversion specifier ends with a format specifier taken from the
The century of the year. This is equivalent to the greatest integer not
greater than the year divided by 100.
+If the @code{E} modifier is specified (@code{%EC}), instead produces
+the name of the period for the year (e.g.@: an era name) in the
+locale's alternative calendar.
+
This format was first standardized by POSIX.2-1992 and by @w{ISO C99}.
@item %d
The year without a century as a decimal number (range @code{00} through
@code{99}). This is equivalent to the year modulo 100.
+If the @code{E} modifier is specified (@code{%Ey}), instead produces
+the year number according to a locale-specific alternative calendar.
+Unlike @code{%y}, the number is @emph{not} reduced modulo 100.
+However, by default it is zero-padded to a minimum of two digits (this
+can be overridden by an explicit field width or by the @code{_} and
+@code{-} flags).
+
@item %Y
The year as a decimal number, using the Gregorian calendar. Years
before the year @code{1} are numbered @code{0}, @code{-1}, and so on.
+If the @code{E} modifier is specified (@code{%EY}), instead produces a
+complete representation of the year according to the locale's
+alternative calendar. Generally this will be some combination of the
+information produced by @code{%EC} and @code{%Ey}. As a GNU
+extension, the formatting flags @code{_} or @code{-} may be used with
+this conversion specifier; they affect how the year number is printed.
+
@item %z
@w{RFC 822}/@w{ISO 8601:1988} style numeric time zone (e.g.,
@code{-0600} or @code{+0100}), or nothing if no time zone is