Interesting, I'm from Hungary (pretty sure that counts as post-Soviet), and I've never heard of such a thing. I'm also pretty sure that the internal passports

Interesting, I'm from Hungary (pretty sure that counts as post-Soviet), and I've never heard of such a thing. I'm also pretty sure that the internal passports are 100% irrelevant to this site and one would get confused by this only if they really, really wanted to.