It is possible to deep link into PDF documents using URLs of the form:
http//example.org/document.pdf#page=7
(for more info see
http://www.planetpdf.com/developer/article.asp?ContentID=6426 ).
In Dokuwiki markup, however, this is not possible for local media files. When # appears in the link location inside {{}} it is squashed to "_" to normalise the wikiname. This is unfortunate.
A workaround is to use an explicit external link that actaully links back into the wiki using /lib/exe/fetch.php. This is, however, very clumsy.