A PDF file is a PDF file, there is no Reader format. And yes, you can do all sorts of things to a PDF. Acrobat Professional has lots of editing tools, there are also third party plug-ins, stand-alone applications, and software libraries for editing various bits of PDF.
What is it that you want to do?
Thom Parker
The source for PDF Scripting Info
www.pdfscripting.com
Very Important - How to Debug Your Script