The snapshot column gives us more info on the pulling and stacking of limit orders. It shows the change in the qty of limit orders at that level since we inside bid/offer last moved up or down.
If we look at the bid side, we can see that:
48 contracts have been pulled from the insided bid (1317.25)
4 contracts have been added to the next bid (1317)
35 contracts have been pulled from the next bid (1316.75) and so on.
On the offer side, we can see that
94 contracts have been added to the inside offer (1317.50)
38 contracts have been pulled from the next offer (1317.75)
20 contracts have been added to the next offer (1318) and so on.
The above example is pretty insignificant, the amount of pulling/stacking(adding) is small. There are times when the stacking and pulling is significant and does tip you off to where the market is heading. Obviously, what is significant differs by market.
For the inside bid, there are two ways you can have the snapshot appear:
Delta – show the net changes to the limit orders, taking into account what has actually traded.
Original – Simply show the qty of limit orders when this price became the inside bid or offer.
The number of levels of snapshot can be set by the user or the snapshot can be removed.