Max labs limit

[paalia]

I'm trying to figure out where/how to edit the max lab limit, e.g. "INDEX-236| "Max labs per area is limited to 1 in 1939"
I've obviously found the index it refers to, but where do I find the index, and how do I edit it?

Just to be clear this is not the same as editing max labs in 'general.txt'..

[special note - I'm running on OSX]

Thanks in advance.