Researching DwgCheck

The TrustedDWG thingy hinges on a system variable called DwgCheck. It's been in AutoCAD since verison 2000, but Autodesk kept it set to 0 (effectively turned off) until AutoCAD 2007.

I've written a longer paper on the history and effects of DwgCheck on drawings from different sources. Here is the summary of what DwgCheck does when opening a DWG file I got from VDraft, the first AutoCAD clone, which was written by SoftSource. (It contains no ODA APIs).

In AutoCAD 2007, when DwgCheck is set to:

0 - Displays the following message on the command line:
Non Autodesk DWG. This DWG file was saved by a software application not developed or licensed by Autodesk. Use of this file with AutoCAD software may result in stability issues.

1 - Displays the AutoCAD Alert dialog box, and the warning on the command line. (The dialog box requires that the user click Continue or Cancel.)

2 - Same as 0.

3 - Same as 1.

In the courtroom, the Autodesk lawyer said the alert could be turned off. It is true that the dialog box can be turned off, but the statement at the command line cannot.