In this mode, you can only place either all buy orders or all sell orders. Buy orders and sell orders can't exist together at the same time.
Unlike One Direction, in this mode you can have open buy and sell orders at the same time.
Similar to Two Directions, you can also have open buy and sell orders at the same time, but any newly submitted order will "net-out" with the oldest opposite open order, becoming one single order with lower quantity. See Position Net-out.