If you want to prove what the rules of a building society are, you can use a printed document that looks like a copy of the rules. This document needs to be certified by the secretary or another officer of the society. They must say it's a true copy of the registered rules. When you show this document as evidence, people will believe it's a real copy of the rules unless someone can prove it's not. This makes it easier for you to show what the society's rules are without having to bring the original documents every time.