Select AutoCAD DXF (or DWG, depending upon what format is required) from the File>Export submenu. The Save As dialog appears.
Using the dialog, indicate a file name to which the selected geometry will be exported. When you select the Options button on the Save As dialog, the Export Options dialog appears. From this dialog you are able to indicate a chord height tolerance, default font name, and version of AutoCAD in which to save the export file. You can also allow external reference blocks to be exported.