Do somebody know the german commando for IPlane or InfinitePlane or where I can find it as a symbol?
Then, while in the command, press F1. that will get you the Help in German (if Rhino is running in German). There you will find the German name of the command and where it is in the toolbars/menus.
The command is called UEbene in German:
Thank you. I tried it with underline and also with the F1 button. Worked!