Tried to respond to this but it didn't post last time, for some reason. Maybe I am just going crazy, sometimes it feels like it.
Not sure if there is more than one numbering system or not. I know 100% for a fact though that Sintax made mistakes in their numbering system. There are some games which have different numbers on the box and manual, respectively, and there are other times where two games share one number. Definitely some mistakes, but for the most part, I think the numbers can be used as a fairly good guide. This is inpart why I have been trying to purchase more Sintax games. I am trying to get a complete set of them, and although I have 35 or 40 different carts, it frustrates me a bit knowing that there are so many out there that I still can't seem to find.