DECC$POSIX_COMPLIANT_PATHNAMES

   With DECC$POSIX_COMPLIANT_PATHNAMES enabled, an application
   is allowed to present POSIX-compliant pathnames to any C RTL
   function that accepts a pathname.

   By default DECC$POSIX_COMPLIANT_PATHNAMES is disabled, and the
   usual C RTL behavior prevails. This disabled mode includes
   interpretation of pathnames as UNIX style specifications and
   uses rules that are different and unrelated to POSIX-compliant
   pathname processing.

   To enable DECC$POSIX_COMPLIANT_PATHNAMES, set it to one of the
   following values:

     1 All pathnames are designated as POSIX style.
     2 Pathnames that end in ":" or contain any of the bracket
       characters "[]<>", and that can be successfully parsed by
       the SYS$FILESCAN service, are designated as OpenVMS style.
       Otherwise, they are designated as POSIX style.
     3 The pathnames "." and "..", or pathnames that contain "/" are
       designated as POSIX style. Otherwise, they are designated as
       OpenVMS style.
     4 All pathnames are designated as OpenVMS style.

   See Chapter 12 of the VSI C Run-Time Library Reference Manual
   for OpenVMS Systems for more information on POSIX-compliant
   pathnames and symbolic links.