Damn guys... it works... in the meantime I was waiting I've tried with two Conditionals operators:www.ossosso.com/scambio/shoot10.JPG
Here the result for this project:www.ossosso.com/scambio/sample.jpg
Even if I haven't a programmer mind this project has been more complicated it could seem.
There are three kinds of width dimension (mixed in the same row), two kinds of armrest (one for the ends and one for the middle) and three kinds of colors.
The build of all the nodes has not been so fluid, probably due to my limitated knowledge of the plugin, but I'd like to ask you a question I have ad after the creation of this project:
-Does is it possible to create a sort of Instance of some nodes? So when I change parameter on one of them it takes effect also on the others. For example when I have a lot of segments sometime I need to use more then one "Linear 1S Generator" into the same RailClone object (indetical Linear 1S Generator), and each time I have to set parameters for each of them.
I repeat: probably my way to set nodes are not "correct" or "professional"
Anyway, thank you very much for your always fast and good support.