The Quick Select Contracts and Contract Settings tab is where you can choose how many contracts you place on the ladder with each click. Here, you can customize how many contracts you place on the ladder with each left click order. In the above Exchange Interface Diagram this is seen in the ‘B’ bounding box.
In this tab you can see a top row with two numbers and a settings cog. The top left number is the number of contracts you have currently selected as your left click value. This number will match the blue highlighted number you have chosen in the Left Click Quick Selects directly below. The top middle number is the total amount of open contracts you currently have open on the order book. This is your right-click value for placing orders. The top right cog symbol is the button to edit the left-click values.
The Depth of market is simply a visual indication of the total amount of contract orders currently placed on the order book.
The total number of contracts at each price increment (tick) is added together and displayed as a depth graph.
This is useful to get a visual representation of locations of resistance or support on the exchange.