Suppose that I wanted to create a custom zone_set, what would the syntax be, what should the filename be and into which folder would it be placed?

Similarly, if I wanted to create a custom district_set, how would that work and where would it go?

Conceptually, I was thinking of creating some new district types such as hybrid energy/mining (maybe a combination of oil wells and oil-burning power plants), hybrid mining/farming (maybe a forest that produces both fruit and lumber for buildings), and commercial districts.

Then using a set of three districts to allow planets to be converted to this new set of three basic districts using a process analogous to terraforming.

Anyone tried something along these lines? Browsing through the common folders I didn't see what I was looking for and the basic mod wiki didn't seem to have anything explicit on this either.

I'm not sure whether it would be better to implement this using zone_set or district_set. Or would it have to be done using planet types perhaps...

Help?