On iOS, people usually refer to RM or Regular Max, while on Android people refer to BM or Base Max. It actually refers to the same idea.
The "Max" part simply refers to the card being fully enhanced. Once the card is maxed, its stats cannot be increased any further (with the exception of the skill.)
- Note: some people refer to RM or Regular Max cards for any regular cards (fresh, half enhanced, fully enhanced). This is because of simplicity:
- there is no abbreviation for a fresh or half enhanced card
- most people just keep a list of reg cards and pm cards they have, and don't take time to differenciate fresh/half enhanced/regular max cards.
- Note: skill on regular maxed cards is pointless in 99% of the cases. Indeed, almost no one uses regular cards to play (except a few exceptions).
- Most URs get a better skill when enhanced (Large becomes Great, Medium becomes Large, etc...).
- Most URs get much better stats when enhanced ( I don't know of any excpetions to this rule)
see Perfect Max