The first line in each of the xml data files appeared as:

<?oxygen RNGSchema="http://francotoile.uvic.ca/includes/schema/francotoile.rng" type="xml"?>

Oxygen (and anything else) is unable to access the rng file using that URL. Greg worked out that this URL is publicly accessible (though never seen by the public) so can be used:

<?oxygen RNGSchema="http://pear.hcmc.uvic.ca:8081/francotoile/rest/db/site/schema/francotoile.rng" type="xml"?>

Edited all the data files to change the first line of the file, updated the svn repository.
The files don't validate against that schema file, so I'll have to figure out what's with that.