Since 2007, the German copyright collective VG Wort has provided a means of receiving remuneration from VG Wort revenues for the use of digitally published documents.
The method involves embedding a tracking pixel (also known as a web bug or web beacon) into HTML webpages so that the number of times the page is accessed can be counted. Opening a page containing a tracking pixel automatically initiates a download request to the VG Wort tracking servers.
However, there are significant shortcomings associated with the use of web beacons in the academic sector. Academic documents are typically made available as PDF documents and tracking pixels cannot be embedded in PDF files, which essentially means that PDF documents are not included in the access count. VG Wort recommends that authors using PDF documents should embed the tracking pixel in the link displayed on the HTML page. This approach has a number of disadvantages:
For this reason, the SULB’s open access servers operate do not make use of VG Wort tracking pixels. If VG Wort decides at some future time to use an alternative request-tracking method, such as that proposed by the German Initiative for Network Information (DINI-AG), the SULB will notify authors that use the library’s publication services accordingly.
Müller, Uwe: Vergütung elektronischer Publikationen in Repositorien - aktueller Stand. B.I.T.online 13 (4) 2010, pp. 391–393. https://edoc.hu-berlin.de/docviews/abstract.php?id=37453