我在AUTODESK的技术支持网站上找到了下述信息：
Issue


You want to create and load a DesignXML file.


Solution


To create and load a DesignXML file, you need to:

Save objects in a drawing as a DesignXML file.
Insert a DesignXML format file in a drawing as a block reference.
To save objects in a drawing as a DesignXML file

On the command line, type wblock and press ENTER.
In the Write Block dialog box, under Source, select the Objects option.
Choose Select Objects to return to the drawing and select the objects to include in the new DesignXML file. Press ENTER to complete the selection.
In the Write Block dialog box, under Base Point, specify the insertion base point for the new drawing using one of the following methods:
Choose Pick Point to return to the drawing and specify the insertion base point.
Enter the X,Y,Z coordinate values for the insertion base point.
In the File Name box, enter a file name for the new drawing, which must include a .xml file name extension. For the file to be DesignXML format, you must use the .xml file name extension.
In the Location box, enter a path for the new DesignXML file, or use the [...] button to browse for a location.
Choose OK.
To insert a DesignXML format file as a block reference

From the Insert menu, choose Block.
In the Insert dialog box, choose Browse.
In the Select Drawing File dialog box, select a DesignXML file and choose OK.
Under Insertion Point, do one of the following:
Select the Specify On-screen option to specify the insertion point when inserting the block.
Enter the X,Y,Z coordinate values for the insertion point.
Under Scale, do one of the following:
Select the Specify On-screen option to specify the scale when inserting the block.
Enter the X,Y,Z values for the scale factors.
Under Rotation, do one of the following:
Select the Specify On-screen option to specify the rotation angle when inserting the block.
In the Angle box, enter the rotation angle.
If you want the objects from the DesignXML file to be inserted as individual objects rather than as a single block object, select the Explode option.
Choose OK to insert the DesignXML file.
在CAD中应该是支持XML格式文件的导入导出的，但是在CAD中无法导入。