4 POSIX specification:@* @url{https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/tar.h.html}
8 Portability problems fixed by Gnulib:
12 Portability problems not fixed by Gnulib:
15 This header file is missing on some platforms:
16 Cygwin 1.5.x, mingw, MSVC 14.