We have just released a new plugin, BookXRefs. This is very similar in
functionality to our BookVars plugin and lets you manage XRef
definitions at the book level. Feel free to download the 30-day trial to
see if it's something that would be useful for your work. For more
information, visit ..
Also, our BookVars plugin has been updated with some new features and
If you've already got a copy of BookVars, you can upgrade to this new
version for free. For the list of changes to BookVars, see the Revision
History link at the bottom of the web page.