Decided to make the related-item linking more sophisticated, so it can use the title of the target document to create the link; that's more meaningful than the xml:id. I've put this code in a separate module which I can use for a range of utility functions later on, to avoid code duplication, and I've also added a link to view the original XML of the document as well as the HTML link -- this is handy for debugging as much as anything else.