Enabling features for Adobe Reader or adding special features for Reader users is a means whereby certain features not appearing in the default Adobe Reader program can be added to PDF documents. This enabling function can be handled by one of two applications. You can use a server product such as the Adobe LiveCycle Reader® Extensions ES or Adobe Acrobat X Standard or Pro.
In Acrobat 7, a single enabling feature was introduced that added these special features to permit Adobe Reader users participation in email–based reviews. When a PDF document was enabled for commenting and markup, all the comment tools appeared in Adobe Reader, they were usable, and the comments could be saved using Reader.
In Acrobat 8, Adobe introduced more enabling features such as those for saving form data and adding digital signatures. These options are not part of Adobe Reader. But when opening an enabled file in Reader, you can take advantage of the special features for saving form data and adding digital signatures.
In Acrobat 9, Adobe broadened the enabling features to include the Acrobat Standard users (Windows only).
As logic would have it, you're no doubt thinking there must be some restriction or limitation on enabling PDF files in Acrobat. After all, how could Adobe hope ...