Looks like Apple or maybe another app on my system decided to remap the file extension to a different UTI, I'll have to dig further to find out. Whoever is responsible doesn't own the type (I don't own it either but I'm also not trying to hijack the file extension). in any case NSDocument/NSDocumentController doesn't appear to be responsible and is in the clear.
Topic:
UI Frameworks
SubTopic:
AppKit
Tags: