Reply to: Support for PI-ModOctober 21, 2014 at 11:04 pm
The following page from 2011 states that “an environment for XMetaL” is available at http://www.pi-mod.de/
I can't seem to locate it, so I would recommend contacting them to ask about it.
Presumably it is some form of “document-level customization” (the term we use to describe all the files needed to help an author editing and work with a particular DTD, which includes at minimum the DTD, a CSS and CTM file but may include many other files depending on how much coding you wish to implement and how much you want to help people by providing features specific to working with the DTD).
To create your own document-level customization you would need (at minimum) the DTD.