Of course, clients never know the facts as well as the lawyers. And lawyers never make mistakes for clients to edit. Yesterday I saw a document which claimed that a security agent had made available a $20 million dollar facility. The term they wanted--and would have corrected, was "Lender." There are a few programs that let you edit pdf's: Flexipdf is one of them. Otherwise, you get a paper copy with edits, or worse, an email with references to lines, which you can't correct because then the pagination changes.