This feature accommodates traders who spread cash against futures, i.e. fixed income instruments against futures contracts of those instruments. The spread order appears in your futures account, and the leg activity happens in the fixed income account.
First, your trading account for futures is linked to a cash account by your FCM. When you trade from the futures account, the appropriate leg is routed to the cash account. Generally, the trading account is the primary account, and the cash account is the mapped account.
Before entering a spread, select the futures account from the account list (right-click title bar to open Account Picker).
Enter the spread (e.g. TYA-BUS10). When you click Legs, one DOMTrader displays the futures leg with the primary account identifier on the title bar (e.g. TYAZ9 on account 12345), and the other DOMTrader shows the cash leg and mapped account (T.US.B035P0819 on account 98765).
For both synthetic spreads and outrights traded on the primary account: if the contract is tradable on the primary account, then the primary account is used. If the contract is not tradable on the primary account, then the first mapped account that allows the trade is used.
Both legs of orders, in any state, are displayed on DOMTrader, Order Ticket, Simple Order Ticket, Order Study, Order Book, QSS, EQSS, and Orders and Positions (Orders and Strategy Manager windows).
Primary account positions are displayed on DOMTrader, Order Ticket, Simple Order Ticket, QSS, EQSS, and Order Book. These synthetic spread positions are calculated as the summary of leg positions in both the primary and mapped accounts.
When the primary account is selected on Orders and Positions, Purchase & Sales, Confirmations, and Open Position Summary display data from primary and mapped accounts. The Statement Report and Current Day Statement summarize primary and mapped accounts, but the Account Value Summary contains data only from the selected account.