No problem with many authors, simply expire when the last author dies. Corporations I sort of already said something about. However I must admit I like how thi

No problem with many authors, simply expire when the last author dies. Corporations I sort of already said something about. However I must admit I like how things work in the Norwegian equivalent of copyright: You can transfer "copyright" to corporations, but if, and only if there is an employee relationship (either you are employed or working as an independent contractor). This for example means that as a student you retain full "copyright" to all of your work (master thesis etc.), but as a professor it can be transfered to the university. In addition you always retain your "ideal rights" no matter what, even if the rest of the "copyright" is transfered to your employee. I don't think american copyright has an equivalent to this. Basically it means that no matter what you have 1) the right to be identified as the creator and 2) the right to deny derivative works to be associated to you. This means that if somebody makes a movie based on your book you can say "Hey, this movie completely misses the point, I don't want to be associated to it in any shape or form" and the creator of the movie cannot use your name at all. This does however mean that there is no such thing as public domain in Norway, since there is no way of giving up your "ideal rights". Even if you put something out there under terms that in the US would be public domain, you cannot give up your right to be identified as the creator or your right to not be associated with derivative works.