When opening a DWG file, various tools are restricted to ensure compatibility with the DWG format . When you are required to create DGN files that are DWG compatible, you can turn on DWG workmode. In both cases, the tools are restricted to create elements that are only compatible with the DWG format. With 3D, this includes the following:

• B-spline curves cannot be used in creating a complex chain or shape.
• Self-referencing of DGN files is disabled, as is reference clipping.
• Raster references are disabled.