It is an anonymous or pseudonymous work and 50 years have passed since the date of its publication
It is a posthumous work and 70 years have passed since the date of its publication
It is another kind of work, and 70 years have passed since the year of death of the author (or last-surviving author)
It is one of "official documents (laws, resolutions, decisions, and etc.), as well as their formal translations; official symbols and marks (flags, emblems, orders, banknotes, and etc.); works of popular art"
