ctype_l(3): Note that not all these functions are specified by POSIX.1-2008.

The function isascii_l() is not in POSIX even though isascii() is,
probably because isascii() is marked as obsolete.  The other functions,
like digittoint_l() and ishexnumber_l(), are FreeBSD-specific just like
their non-_l versions.

lib/libc/locale/ctype_l.3

@@ -135,4 +135,17 @@ See the specific manual pages for more information.
 .Xr xlocale 3
 .Sh STANDARDS
 These functions conform to
-.St -p1003.1-2008 .
+.St -p1003.1-2008 ,
+except for
+.Fn digittoint_l ,
+.Fn isascii_l ,
+.Fn ishexnumber_l ,
+.Fn isideogram_l ,
+.Fn isnumber_l ,
+.Fn isphonogram_l ,
+.Fn isrune_l
+and
+.Fn isspecial_l
+which are
+.Fx
+extensions.