[W]

[..]
  1. WAKEUP_CHARS
  2. WCOREDUMP
  3. WEXITSTATUS
  4. WIFEXITED
  5. WIFSIGNALED
  6. WIFSTOPPED
  7. WIN_DIAGNOSE
  8. WIN_FORMAT
  9. WIN_INIT
  10. WIN_READ
  11. WIN_RESTORE
  12. WIN_SEEK
  13. WIN_SPECIFY
  14. WIN_VERIFY
  15. WIN_WRITE
  16. WNOHANG
  17. WRERR_STAT
  18. WRITE
  19. WRITEA
  20. WSTOPSIG
  21. WTERMSIG
  22. WUNTRACED
  23. W_OK
[..]