[Zope] Filesystem Page Template lowercase-ifying all my tags

I have a product that installs some filesystem page templates into a plone site's portal_skins. The templates are exactly the same as their created-through-ZMI counterparts, yet the filesystem templates render with all their tags lower-cased, whereas the ZMI-created templates preserve case. Why is this happening? Zope 2.7.7-final, python 2.3.5, freebsd5 Page Templates 1.4.0 Thanks! fm