When building an XML Publisher report, I spend most of my time working with the Word Add On. Since everything is local, it's easy to make a change to the report then test it with the Preview feature. However, if the report includes sub-templates, then there's a small difference in the reference to the sub-template.
Here's what the reference to a sub-template looks like when it's stored on the server:
Here's what the local version looks like:
Note that the stored reference uses the Sub Template Id, while the local reference just uses the file name.