To prevent the user from fixing ambiguous template matches (they are not presented to the user by the XProc processor), the templates automatically got a priority assigned, meaning templates placed below are more important than those placed above. This can be cumbersome and I think I’ll drop this with the switch to XProc 3.0.

When other configurations are imported, they are merged together into one XSLT stylesheet and the templates of the importing configuration are assigned with a higher priority than the imported ones. This makes it harder to selectively override imported templates. But it’s currently not possible with XProc to reference within a dynamically generated XSLT other generated XSLTs as imports (except when written to disk, which is too “antsy” for an XProc guy).