Pre-trade FX

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With simple architecture, it is possible to use OACT to process non base-currency trades.
In a scenario where a $ denominated Item is ordered for an amount in €, the following flow can be created with good integrations.

1) An order interface (not OACT) receives an order to buy "$ item" for €100
2) The interface creates an Order in OACT: Buy $ for €100
3) The Order is Aggregated and Confirmed in OACT. The resulting transaction has purchased $200 for €100
4) An integration creates a new Order in OACT: Buy "$ item" for $200, including a relevant "order_comment" to provide information downstream about the FX trade and rate
5) The Order is Aggregated and Confirmed in OACT, and becomes a transaction.
6) The order interface receives complete information to present the trade.

(the flow in complete reverse, where € are to be received from the sale of a $ item.)

Both parts of the above flow, i.e. ① FX and ② Trade can be handled in a single installation of OACT, though "Stacking" might be beneficial in some situations.