When Acrobat appeared, I made a web with many PDF documents. Some of these
were very big, so I splited them in many little PDF files (for ex. one file for
every chapter) and the first uses the URL method to link the others (like
in HTML files)
What's the problem?
Now many Intranet search engine support PDF format but the spider (crawler) can
only find the PDF files linked directly by a HTML files.
The other PDF files are HTML-orphans.
How can you resolve the problem?
1) You can use a different approach like byteserving method
   (http://www.adobe.com/prodindex/acrobat/byteserve.html). With byteserving
   method you can maintain big PDF files.
2) You can create an ad hoc HTML file for your PDF files
3) IndexMaker can create for you an HTML file for your PDF files
