FX notation confusion
So I thought I understood the concept of exchange rates correctly but this still confuses me. As far as I have understood, CFA uses the direct quote (Price/Base), where Price is the domestic currency and Base is the foreign currency, and it all works well for most questions, especially in economics.
However, for no-arbitrage currency forwards I have noticed that they sometimes treat the price currency as foreign (indirect quote). We use rf − rd in the formula, and while USD is the price currency, it is used as the foreign currency in the solution.
Can anyone guide me on what the correct notation is in these cases (how do I determine from such questions which is foreign and domestic), or am I correct in understanding that CFA reverses the notation between these two concepts?