Rule 644 A book, purporting to be printed or published by public authority, is presumed to have been so printed or published.

If a book claims to be printed or published by a government or other official authority, the court will accept that claim as true without needing extra proof.

This means that if someone brings an official-looking government publication into court, no one has to go out of their way to prove it is real. The court simply treats it as genuine based on what the book says about itself.