iswxdigit
=========

POSIX specification: http://www.opengroup.org/susv3xsh/iswxdigit.html

Gnulib module: wctype

Portability problems fixed by Gnulib:

  * This function is missing on some platforms: IRIX 5.3, Solaris 2.5.1.

  * This function returns 0 for all possible arguments on some platforms: Linux libc5.

Portability problems not fixed by Gnulib:

  * On Windows platforms, wchar_t is a 16-bit type and therefore cannot accommodate all Unicode characters.