Copyrighted materials are protected from unauthorized changes and use. Simple stuff.
Not really so simple, if you read the other discussions we have ongoing.
Is it a violation of copyright law for me to tear pages out of the paperback I just bought?
Is it a violation for me to pay someone else to tear pages out of the same book?
Is it a violation for me to pay the book store to tear pages out of the book at the time I purchase it?
If hundreds of customers regularly want the same book with the same pages torn out of it, is it a violation of copyright law for the book store to simply keep copies of the book available for sale with the pages already torn out?