What determines the regulation marks on cards?

https://preview.redd.it/hkbqv82jrogg1.png?width=405&format=png&auto=webp&s=5b1a378ef417a3085d08a0bf90cbf8b81f1bd58a

https://preview.redd.it/34qw1z2lrogg1.png?width=403&format=png&auto=webp&s=01c4ede4c693c75f13fb7ae46f24ea6a6cc6e1be

Ultra Ball is 'I' and Black Belt's Training is 'H' even though it was released AFTER the ultra ball - surely both are considered "reprints" as ultra ball has also existed before.

Help a confused dude!