WMFBKGND system variable
Function Description:
The WMFBKGND system variable is used to control the display of background when inserting an object as WMF format.
Type : Integer 
Saved in : Not saved 
Initial value : off
Users could use one of the following way to insert objects: 
Export WMF file by WMFOUT command 
Copy to clipboard and paste as WMF files 
Drag as WMF files