Thanks for the explanation, Laurent. But I'm quite sure that this feature is not really archieving it's goals. As I see the .dat-file is (at least on my current track) not affected by the lock, so there is still no problem to insert my name as an author. And even if.. I just checked it: Editing the 'GP4 Infos extended data' via a HexEditor is as easy as sitting on the couch. The track can still be duplicated and be sold via e.g. Ebay and so on. So I'm not sure, whether this feature is impeeding re-selling tracks more than track editing in general.
I'm still very, very, very unhappy about this feature, especially looking at our community, which has been left by so many authors. Now their files are uneditable for all future and the locks of track will even speed-up this process, I think. As it seems, no-one ever thought out this feature. And the fact, that there are just very few tracks locked, is no positive point for this feature at all. Sorry Laurent, but there is nothing else I can say. The final point is about the -except this point great- GP4Builder's guide. That files can be locked is just mentioned in the guide, but not how.
Sorry for this argument, but I think it's always the best decision to critisize crucial point, than to keep silent looking at a development into a wrong direction.