int pppclose __P((struct tty *tp, int flag));
int pppread __P((struct tty *tp, struct uio *uio, int flag));
int pppwrite __P((struct tty *tp, struct uio *uio, int flag));
int pppclose __P((struct tty *tp, int flag));
int pppread __P((struct tty *tp, struct uio *uio, int flag));
int pppwrite __P((struct tty *tp, struct uio *uio, int flag));