It is an anonymous, pseudonymous or posthumous work and 50 years have passed since the date of its publication
It is another kind of work, and 50 years have passed since the year of death of the author (or last-surviving author)
If it's laws and regulations and officially published preparatory work therefor, decisions of the courts and of administrative bodies and official translations of such texts ; the news of the day published, diffused or communicated to the public.
