FIFOPOLLW
if ((fnp->fn_flag & (FIFOISOPEN | FIFOPOLLW)) ==
(FIFOISOPEN | FIFOPOLLW)) {
if (fn_dflag & FIFOPOLLW)
fn_dest->fn_flag = fn_dflag & ~(FIFOWANTW | FIFOHIWATW | FIFOPOLLW);
fnp->fn_flag |= FIFOPOLLW;