When a transaction is settled in a different currency from the one in which it was denominated, an FX difference arises between the transaction currency amount and the settlement currency amount. This difference must be recognized as a realized FX gain or loss. Settlement currency is the point at which the obligation moves from accounting record to actual cash movement.
Position in Chain
Settlement currency is State 03 of the CCY State Chain. Cash moves. The obligation is discharged. If settlement currency diverges from transaction currency, an FX consequence is realized.