There are a few strange stories that haunt the history of CAD, and one of them is Autodesk's attempt to register the ".dwg" file extension as a trademark in the USA and other countries.
(In brief, the USPTO hasn't been inclined to grant Autodesk's registration request, since file extensions cannot be registered. Along the way, Autodesk has sued out of existance attempts by other CAD vendors to use the letters D-W-G in product names, or paid them to stop.)
I thought the whole matter had ended when SolidWorks and Autodesk came to a surprise agreement early in the morning before a court trial was to begin over "DWGEditor" and other verboten names SolidWorks had registered. That was 23 June 2010.
(Later, we realized that the capitulation by SolidWorks came about because they had an ace in their pocket: they had signed an OEM agreement with Graebert to license ARES under the name of "DraftSight." Coincidently -- or not -- Graebert has spent the last many years in German court fighting Autodesk over another issue. Revenge tastes best when served piping hot!)
It had been a year since I last looked at the "DWG" file at the USPTO, and so I was very surprised this morning to learn that Nemetschek Vectorworks had also filed an objection last March. (CEO Sean Flaherty protested Autodesk's attempt to register DWG.) Two month later, the USPTO decides it agrees with Vectorworks, adding that there are reasonable grounds for refusal.
On August 24, the USPTO wrote Autodesk's external law firm (Wilson Sonsini Goodrich & Rosati) that they had six months to respond, or else Autodesk is deemed to have abandoned its registration attempt of DWG.
The six-month deadline is next week, Thursday. We'll have to check back on Thursday to see whether or not Autodesk has given up on registering DWG as a trade mark.