Internet-based teaching using PDF-documents

The Portable Document Format (PDF) is very popular for distributing information over the Internet. It is often used as primary document format for lecture notes. Unfortunately there are many problems related to the format if it is used in context of an interactive teaching and learning environment. In such an environment it is necessary to personalize content for each user. Documents must be adapted to user's preferences. In this article we claim, that '' ordinary '' PDF is not optimal in that context. Documents must be enhanced. We take a look at features of PDF and will discuss problems when exploring the content of such a document. A simple solution for adding notes to PDF is presented. Since it is not possible to add notes to documents using freely available PDF-viewers we propose a server-side application to support readers of documents.