To open a DOM on the Bookmap platform, users will need to “subscribe” to the futures symbol of their choice.
1. Left click the + button located in the top left corner of the platform window or use the shortcut Ctrl + T.
![Bookmap DOM 1](https://support.optimusfutures.com/hubfs/Bookmap%20DOM%201.png)
2. With the Subscribe window open, first select the data feed you would like to use under the Platform field. Once a data feed is selected, search through the dropdown menu or manually enter the futures contract you would like to trade under the Symbol field.
![Bookmap DOM 2](https://support.optimusfutures.com/hubfs/Bookmap%20DOM%202.png)
3. Left click the Subscribe button once the appropriate fields have been entered. This will open a DOM on the right hand side of the window for the related futures instrument that was chosen.
![Bookmap DOM 3](https://support.optimusfutures.com/hubfs/Bookmap%20DOM%203.png)