Terms of trade definition in a two-country DSGE model

Dear Johannes and other scholars,
First thank you very much for your previous guidance, I am grateful.
I am currently formulating a two-country DSGE model and involves terms of trade, however, I am confused about this concept, in some DSGE model papers, they model terms of trade=export price index/import price index, while some other DSGE model papers, they define terms of trade=imported foreign price/domestic price, I am wondering that which one is the correct form for terms of trade in a two-country DSGE model?
Thank you very much and look forward to hearing from you.
PhD Candidate

It’s a matter of convention whether you define the terms of trade as import over export prices or the other way round. Similarly, you can define the exchange rate as domestic currency over foreign currency prices or the other way round. You just need to be consistent.