Batboard

Ok, does anybody know what Indexing Keys really do? just wondering, cause am reading through the keyloader manual and they talk about that, and on the AS3, it has indexing too, am trying to figure out what it is really

Is indexing mean just putting 2 keys each in 1 group like saying 2 keys for Police, another 2 keys for Fire, and so on?

Ohh before I forget to ask too, soo if its index like that, does the key switch back and fourth?