WR_ISACK
ASSERT(!WR_ISACK(dur));
ASSERT(!WR_ISACK(pth));
if (WR_ISACK(dlr)) {
ASSERT(!WR_ISACK(wn));
if (WR_ISACK(dlr)) {
ASSERT(WR_ISACK(wn));
ASSERT(WR_ISACK(dur));
ASSERT(WR_ISACK(dpth));
dir = "><"[WR_ISACK(&wn) != 0];