can somebody tell whether you need to follow the contour lines point by point or whether it is possible to select the line, make sure that all points are in the same z-position and then give a command like "create a plane from the closed line"?
I have got topography lines that are very detailed and I think it's unneccessary work to draw the plane by following the line but I just can't find the right command.
thanks a lot

Not sure of the exact
Not sure of the exact scenario you describe, but there a couple of switches for making a line open versus closed, and a plane versus a line.
If you select your line and then go to the Selection Information panel, then scroll down until you find the section for Modelling Flags, then change the settings for "Closed" and "Planar" to both be true -- this should give you what you want.
Please search before posting a question.
better late than never
thanks for your suggestion, i've already used it a couple of times.