Adobe Acrobat 7 Professional - Manual (Page 40)

Additional usage rights
You can assign special rights to a PDF document, making more tools and features
available to users of Adobe Reader and letting them save the data that they type in a PDF
form, sign documents, participate in online document reviews, and attach files to a PDF
document. If a user opens a document that has these additional usage rights, a yellow
Document Message Bar displays the additional tools required to work with the document,
and Adobe Reader provides instructions.
You can add commenting capabilities for email-based reviews directly from Acrobat
Professional. You add other additional usage rights by using a server extension. For more
information, see the Adobe website at
www.adobe.com/products/server/readerextensions/
main.html (English only).