Hi,
I need the SE to index big PDF documents. What I can find out about your SE so far is, that if the user found a matching PDF and follows the Link, he has to search inside the PDF again :-( 
I know, that you can add Parameters to the PDF, so that it performs an document search when the file is opend (i.e.: http://www.yoursite.de/archive/pdf/test.pdf#search="tree")
Not all of the SE query syntax possibilities can be used I think, but is there a possibility to enhance the PDF Search this way?