So hypothetical situation:
I buy one of the DLC kits from steam that gives platinum that you can't trade. So after buying some stuff, I'm left with 100 in non-tradable platinum.
Then I buy 75 platinum from the website that I can trade with people, so now I have a total of 175P.
My question is; does the game distinguish these? Like if I buy a blue potato from the store worth 20P, does it deduct from the tradable or non-tradable platinum first? And is there a way to know how much I exactly have in each when I trade stuff?