There are a growing number of alternative TAL (Template Attribute Language - the heart of Zope's Page Templates). One of these is OpenPT (previously known as AltPT). The curious thing is the feature bullet cited below:
OpenTAL can now read template configuration in the form <tal:config property="value" multiproperty="value1;value2" />. OpenPT uses this to possibly set properties (like encoding, handlers, preferred output encodings) via source; useful for webdav/ftp editing [Lalo Martins]
A good idea, but I'm not sure if it's the right implementation. It seems that since TAL does such a good job being a good XML/HTML player, something like this is best suited to processing instructions, something like <?tal config property="value" multiproperty="value1;value2" ?>. Of course, we'll have to remind the HELL out of people that <?tal is not PHP.