Hello Francesco,
throw an eye over, "keyword Surface Class A" here (I like this page!)
http://www.kodg-3d.com/en/tutorials/aliasvsrhino/45-class-a.html

and determined by the same designer from Russia, you can adapt some things in moi3d.
(is relevant only up 3 minute until minute 37, rest are not native commands, tut. only in russ-language)
https://www.youtube.com/watch?v=SXUf6MXDzA0
regards

many thanks :)