VMS Help CC, Run-time functions, iswspace  *Conan The Librarian (sorry for the slow response - running on an old VAX)

  Returns a nonzero integer if its wide-character argument is classed
  as a space character in the program's current locale.  Otherwise,
  it returns 0.

  Syntax:

       #include <wctype.h>  (ISO C Standard)
       #include <wchar.h>   (XPG4 Standard)

       int iswspace (wint_t wc);