Usage: CLIENT <class> SET LIMIT <number>

This command limits the number of clients that can connect with this profile. Warning: If you do not have any other profiles defined then the number set will be the maximum number of users allowed on the server. You will probably want your z-default to allow as many connections as you can, but remember if a client hits an earlier limit, then they cannot get onto your network.

/as client WebMaster set limit 100

You can use this to limit certain types of users so that other preferred users are more likely to be able to connect. Or you could set your z-default to a smaller value than your total allowed client amount. Then you can have an earlier profile allow on your full amount so that people in that profile can always connect since space is reserved for them. You'd want to place your profiles and set your limits carefully to arrange that.