I have a file that has gotten quite large as I have used several background bitmaps to help sketch curves. I now want to delete the bitmaps from the file. The backgroundbitmap remove function just removes the image from the viewport. I use the audit3dmfile command on the resaved file, and the bitmap(s) are still shown in the bitmap table. How do I strip these bitmaps from my file without removing all my other plug-in data?