AFAIK, no. If you write a model or specification in, say, UML/TLA+ the specific code will be GPL, but not the "by-products" of it. Also, you wouldn't know how to prove someone used the specification in the first place (unless he wrote in a design by contract language, such as SPARK). Also, LGPL permits to close the code, only GPL that doesn't.
True, LGPL does permit that, but it says if you make changes to the code, you must share those specific changes. I guess mlv_structure.h is shared with LGPL so that if anyone makes their own changes to the format, they must give back... but I just see many ways around it. And if the "change" is adding a new block, it could just be put in a separate file, and the LGPL does not even apply, so adding a proprietary block would be easy and we don't have a way to control that if someone does it.
So it feels like having a license on the MLV structures does nothing.
Why that worries you? Or the question was just out of curiosity? If someone wants to implement another MLV encoder/decoder, I don't see a problem in that, this is exactly what open source should want, people freely sharing information.
Nothing worries me, I have had a lot of different thoughts about this issue. At one time I was thinking about making an mlv structures header file with a license to match the rest of LibmLV, but it's too weird to me so I'm not going to bother.
And what about these evolutions of my question:
1. Someone looks directly at the mlv_structure.h LGPL header, writes it down on paper, and later rewrites the structures in C based on their paper notes, is their code under LGPL?
2. Someone looks directly at the mlv_structure.h LGPL header, and rewrites structures in C while looking at the original structures, is their code under LGPL?
3. Can structures even be put under a code license like GPL/LGPL? They are not code, but descriptions of how some fields are arranged in memory/files right? Or are they considered code?
