For the CAD export a header file (as dxf or dwg) must be defined. For this either an existing file can be used or a new header file can be created.

A new header file is created as follows:

•Open your CAD program (e.g. ACAD).

•Save the empty file as dwg or dxf.
The version number depends on the version you are working with. I.e. if the CAD drawing is saved as Version 2011, it will work for 2011, 2012, 2013 and 2018, however not for older versions.