How is TriPOS Cloud tied to a merchantid?

I'm at the beginning of looking into a TriPOS Cloud integration and I'm trying to figure out how a terminal is tied to a merchantid.  I'm used to some other vendor integrations where you have account credentials/api keys, etc and then when you make api calls you can specify what merchantid to use.  Sometimes its tied to the terminal or you can specify on the request.  I have not seen anything in triPOS Lanes api or the triPOS transactions api that let you specify a merchantid.  Is it just the same as the accountid and so every merchant would require different credentials?