Thank you so much for answering me.
the solid was first generated in orderly mode, as thickness of a surface.the surface was created as bluesurfing... later it was converted into synchronous mode.
Do you think there might be a way to correct or allow modification? I tried to build a solid on it, but the problem remains. I tried to combine surfaces, solidifying them...but the problem persists. . .
I'd like to try to recover the solid if it was possible. When I used nx, I could shoot it, and often, so I would eliminate these math things. .
Gabriele