Hi!
Thanks! I tried to convert the file in another cad software and if I used a new dxf-format the splines are still there and appear as straight segments in TBC but if I save it as an older dxf-format the splines are converted to many small segments and that works. The only problem with that is that the file becomes 25 times bigger. But now I can use the file and if I want it smaller I can always use the convert linestring-command to filter out segments.