Document to document cross reference links do not work when saved to PDF?

I assume that each of your documents is a FrameMaker book file, with its components in separate FrameMaker documents.

From memory:

• You must name each of your book files the same as the PDF you will output from it
  (i.e. foo.book for an output of foo.pdf)
• You must not link across drives
  (e.g from a network drive to a local hard drive)
• You must open the book file that you want to output
• You must also open any book file that contains a component to which you are linking
• You do not have to open the components themselves
  (i.e. the *.fm FrameMaker documents)
• You must use the default output name for the PDF
• All PDFs must be in the same relative location as their corresponding book files.

Most people put the book files in the same directory, and output the PDF files to the same output directory.

If you rename the PDF files, or change their relative position, you will break the links.

re: Document to document cross reference links do not work when saved to PDF?

Are you just trying to open the target PDF, or go to a specific marker (page) within it?

If the latter, see How do I create links from the middle of 1 PDF to another? among other discussions.

I have no idea if this was ever fixed in more recent versions of FM i.e. could be done without PDF hacking or 3rd party tool.