Internet Cases:  “One of the issues in the case of Autodesk, Inc. v. Dassault Systemes Solidworks was whether Autodesk could claim trademark rights and the letters ‘DWG‘.  The .dwg (‘drawing’) file extension is the native file format for Autodesk’s flagship product AutoCAD.  Plaintiff Autodesk moved for summary judgment on the trademark issue.  The defendant pointed out that the trademark laws do not permit one to claim exclusive rights in trademarks that are merely functional.”