Ex. say you over 50 yrs old and are playing on a 40M team, you CAN play on a 50M team but count as 1 of 3 out of Ratings players but you CAN'T play 50AAA (technically 2 levels by their RI). Same with say you are a 50M+ player, you COULD play 40AAA and count as the 1 of 3 out of Ratings players.
Also, once you play in 2 events for a team, then you would hold that Ratings for the year and 2 more years.
It's all about what they call their "Rating Index" (RI). Highest is a 10 which is 40M+ player.
Not sure what USSSA will do and ISSA is tarting to keep track but not as stringent with the application.