Transaction / Position

 In order to complete a transaction we need to perform a purchase and a sale. If a purchase and a sale were not performed, then the transaction was not completed, and it doesn't matter if you are going to gain or lose in the course of the transaction.

Remember, this is an important rule: realization of the gain or loss occurs only when the transaction is complete. 

Position is in essence a transaction.

Opening of the position - opening of a transaction for a currency pair.

Open position –a position which hasn't yet been closed, in other words, the transaction has not yet been completed.

Closed position –a transaction which has been completed, the actions of purchase and sale have been performed.