I posted the english Zaxxon's explanation (copy-paste) on the rallysim forum Here is the link (http://forum.rallyesim.fr/viewtopic.php?f=51&t=2312).
On the spanish forum "simracing, you have an Spanish explanation (use google to translate because I don't know your mother tongue ;-) ) with some interesting files...
http://foro.simracing.es/bobs-track-builder/3897-rbr-cielos.html#post49787
If you want more information, ask Zaxxon or Eno, their last creation have got amazing sky. They look very nice and I'm sure they will help you.
thank you very much these links
and now found a great new rallyesim forum:good: