[itsme]

No. I'm talking about a link to a locally stored .MSCZ file. In the first step it is required to be stored in the same folder as the PDF.
The attachment BeiDirWarEsImmerSoSchoen.ZIP in http://zubersoft.com/mobilesheets/forum/...p?tid=3161 contains such a pair of .PDF and .MSCZ if you want to try it.

Here's how I created that link:
I open the PDF with the free "PDF-XChange Viewer" http://www.chip.de/downloads/PDF-XChange...39244.html  to add the link.
From the menu I select "Tools – Link Tools – Rectangle Link Tool" and add a rectangular link.
Then I open the link's properties window and select the "Open a file" action via "Actions - Add 'Open a file'...".
Another follow up window opens where I select the MSCZ file, and set "Open In:" to "Window set by user preference" and "Operation:" to "open".
From the "Appearance" menu you can set a frame around the link or add a textual comment via "Comments" to make the link visible.
A bit complicated, for now. I just wanted to see if it works. I'm looking for an easier way to do it.