A long black day is followed by a black day that gaps below the first day.
The next two days continue in the same direction with lower consecutive
closes. The final day is a long white day that closes in the gap between
the first and second days.
In a downtrend or within a pullback of an uptrend, the stock exhausts
itself with a gap down, but although the downward movement continues,
it slows noticeably. The long white day suggests a possible reversal in
the making to at least fill the overhead gap. Declining volume on the
three middle days with a pickup in volume on the white day serve as confirmation.