You can create links to both page numbers and "named destinations" in PDF documents. The procedure is the same for links that will be used in PDF files and in WebHelp output.
Named destinations are jump targets that work like anchors. These links will work in PDFs created by Help+Manual and in WebHelp created by Help+Manual, but not in CHM files. The Microsoft CHM viewer does not support the link format needed to jump to destinations in PDF files. A link to a PDF in a CHM file will simply open the PDF at the first page. See Named destinations in PDF for details on the named destinations created in PDFs by Help+Manual and more background information.
Note that named destinations are only needed for links between two different PDF files or from other applications or documents. Use normal topic links to jump to targets within your Help+Manual projects (i.e. from one topic to another). You don't need to use named destinations for this.
•File Links are required for linking to PDFs:
You must use the File Link option for creating links to targets inside PDF files. The Internet Link option will not always work correctly, even in WebHelp.
•Set the PDF to "interactive" to use named destinations:
If the PDF you are linking to is created with Help+Manual it must be generated using the "interactive PDF" option in your PDF settings. Named destinations are only generated for interactive PDF documents.