Here you can get information about the structure of a transaction in the BFS.
Asset1 and Asset2
A transaction in the BFS often consist of two legs called Asset1 and Asset2. What you assign to these two depends on what transaction you are trying to create/get in the API. The following rule can be applied:
Always assign currencies to Asset1 and instruments to Asset2 if both types are included in the transaction.
In some special cases Instruments or currencies will have to be assigned to both of the legs. Currency exchange is one example of a transaction of that kind. In that case you have a transaction with two different kinds of currencies and will therefore be forced to assign currencies to both of Asset1 and Asset2.
There are certain cases where only one leg is sufficient to describe a transaction. An example of this is a deposit transaction where only Asset1 is needed.
Asset1 and Asset2 only describes the type of currency or instrument. There are two additional input parameters that describes the amount of Asset1 and Asset2 respectively. These two parameters are called AmountAsset1 and AmountAsset2.