Tags to allow re-use of content from other documents

Hi all,

I am looking to determine if there any tags that can be applied to a Docbook
book that will allow re-use of content by another Docbook book? 

We will be creating the source docbook xml document from a modelling tool
that contains some comments and want to re-use these comments as paragraph
text and glossary entries in a target book. We hope that by doing this it
will allow us to maintain the comments in the modelling tool and keep the
target Docbook file that uses this upto date with minimal intervention. 

Also, could there be any implications for subsequent HTML or PDF outputs?

Thanks and regards
Chris