The jboss-ds_1_5.dtd (as distributed in docs/dtd/) is wrong or not up-to-date (and there is no newer version and no out-of-date mark). As has been pointed out by Adrian Brock in
JBAS-4942, it is possible to specify a loader-repository like this:
<!-- The loader repository name used by the ear -->
<!-- The "path" to the rar -->
... although this is not compliant with the DTD!
Keeping the DTD up-to-date would avoid unnecessary bug reports and/or forum questions because looking at the DTD is the first step in finding out how to configure required behavior.