-but even if it is not, this function is still implemented (although support
-for locale-dependent format specificators such as {\tt "\%c"}, {\tt "\%x"} or
-{\tt "\%X"} may be not perfect). This function does handle the month and
-weekday names in the current locale on all platforms, however.
+but even if it is not, this function is still implemented, although support
+for locale-dependent format specifiers such as {\tt "\%c"}, {\tt "\%x"} or {\tt "\%X"} may
+not be perfect and GNU extensions such as {\tt "\%z"} and {\tt "\%Z"} are
+not implemented. This function does handle the month and weekday
+names in the current locale on all platforms, however.