I knew this information bro. I'm just talking about CS:GO. Here in CS:GO it's used to separate World on some regions, like NA, SA, EU, Asia etc.
So which region would you choose for Ukraine? To whom we belong? We are not NA, not SA, not Asia, at least right know not EU (not yet). So for sure we belong to something like "CIS". I mean we belong to it not politically, but regionally and territorially. I don't like this abbreviation too, but it's kinda correct in this case.