Trademark protection of File Extensions in Europe

US CAD company Autodesk's efforts to monopolise the ".dwg" file extension via a pending US “DWG” word mark application (No. 78 852 798) claiming all kinds of "computer software", have, even though the USPTO has not yet issued a final refusal to register the mark, meanwhile led to the satisfactory result that file extentions cannot be trademark protected in the US (see, e.g., here, here, or my earlier post). Even though Autodesk had to disavow the US lawsuit Autodesk vs DS SolidWorks that, as fas as Autodesk is concerned, anyone in the world is free to use “.dwg” as a file extension (cf. doc 241, filed on December 31, 2009; see also here), a file extension is in fact to be considered descriptive and/or generic due to its functional use, while it is a fundamental rule of US trademark law that trademark protection is not issued on symbols or marks that are entirely functional. In Europe, Autodesk applied for a Community Trademark "DWG" (No. 004703641) claiming, inter alia, "Computer software; computer aided design software; software developer tools; software for sharing information in a secure environment; downloadable software", which meanwhile has been withdrawn after two oppositions filed by opponents "Knowledge Base Software (Pty) Ltd" and "DS SolidWorks Corporation" and a subsequent appeal. In Germany, two parallel “DWG” word marks are currently pending - No. 3020090602751 and No. 3020090276943 - the latter being a conversion of the withdrawn CTM registration -, both claiming computer software, CAD software or the like, which may, if granted, potentially be used to prohibit usage of the “.dwg” file extension in Germany. However, even though Autodesk's respective disavowal in the US lawsuit is irelevant in Germany, Autodesk's German trademarks most likely cannot be used to obstruct using “.dwg” file extensions, since appropriate legal measures and arguments exist to both attack a potentially granted mark and, if necessary, defend against an infringement threat. File extensions are technical indications of a file's format and, as such, cannot be registered due to absolute grounds for refusal according to § 8 II MarkenG (German Trademark Act), since, in my opinion, such signs are devoid of any distinctive character (§ 8 II, 1) and/or consist exclusively of indications which may serve to designate the kind, intended purpose or other characteristics of the claimed goods or services (§ 8 II, 2), in analogy to the related US doctrine. Autodesk may still argue that, according to § 8 III MarkenG, “DWG” has established itself in affected trade circles as distinguishing sign such that possible absolute grounds for refusal have been overcome. In fact, Autodesk has already argued along this line in the above-mentioned US lawsuit Autodesk vs DS SolidWorks (cf. doc 1, Complaint, filed on September 19, 2008; see also here) by asserting that design professionals would recognize “DWG” as the name of Autodesk's proprietary technology and file format (doc 1, §§ 9…