Open a files in emacs-wiki with external applications

Hello!

Is it possible to open a file clicking on a link in emacs-wiki
mode with approppriate applications? 

Say one want to open a PDF file but with evince, or file.sch with
gschem application. Can one open these files with evince and gschem
respectively? 

Any advices will be appreciated!

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Regards, Paul Csanyi
http://www.freewebs.com/csanyi-pal/index.htm