@Georges and Michael
Yes it's that :) (and yes I can use the 3dm2dxf but...
like for this file;) (and yes it's more easy to make the plane inside Moi but...
as Moi has more efficient tools 2D for make any drawings of lines boolean in one pass!
( in Ketchup you must erase by hand the lines intersected! ) that will be useful to have a direct export skp ;)
...and sure that is not vital ;)