MAXACKWINDOW
(ackskew >= -MAXACKWINDOW) &&
(ackskew <= (MAXACKWINDOW << sws)) &&
SEQ_GEQ(src->seqhi + MAXACKWINDOW, data_end) &&
SEQ_GEQ(seq, src->seqlo - MAXACKWINDOW)) {
(ackskew >= -MAXACKWINDOW) ? ' ' : '3',
(ackskew <= (MAXACKWINDOW << sws)) ? ' ' : '4',
SEQ_GEQ(src->seqhi + MAXACKWINDOW, data_end) ?
SEQ_GEQ(seq, src->seqlo - MAXACKWINDOW) ?' ' :'6');