FOSS gamedev and creative worlds

Just magically after posting this, a thread with the same question and the answer showed up. ] :

viewtopic.php?f=3&t=13132&hilit=perlin+noise

[I recently found a link somewhere in the forum to a file which explained the different variables when registering a biome.
Unfortunately I can't find it anymore, not in the forum, nor by using a search engine.
I found the reference/tutorial very helpful and I would greatly appreciate it if someone could come up with the link to it.]

Jordach's manual only applies to 0.4.12 though, the 0.4.13 system is different in some ways and more stable (system has now settled down and is less likely to change).