In GP, a General Ledger Account has the ability to assign which Currency Code(s) are allowed to be used in a transaction. The GP window is under Cards > Financial > Account Currencies. This function restricts users from posting transactions in Currencies that are not assigned to the GL.

It would be nice to have something similar in Business Central as this has came up a few times in our GP to BC migrations. GP migration clients are asking for this because they have GLs that are currency specific. For example, they may have an AP GL that is for USD transactions only. Therefore, they would want only USD transactions posted to that AP GL.