DocBook Comparison Concepts
DocBook Comparison highlights changes between two DocBook files. It performs a detailed comparison between the two files and automatically adds revision flags to highlight added, deleted or changed text. Alternatively, DocBook Compare can be configured to output the differences in some XML editor specific 'track change' formats.
You can show the changes in any colour or text decoration by modifying your publishing pipeline. Whether you are publishing to the web or printed page, you can highlight changes with DocBook Comparison.
The DocBook Comparison Configuration reference gives the details about all the configurations.