I used it on a popular wiki for adding metadata that allowed for decently powerful search filterings. It was important to do this because mediawiki's default s

I used it on a popular wiki for adding metadata that allowed for decently powerful search filterings. It was important to do this because mediawiki's default search is/was absolutely horrible. We never bothered doing anything like concepts, detailed types, etc...we only used it for basically adding tags to pages that you could query as part of a search. It worked okay with that. We had some issues where we wished a property could be an enumeration or nullable, which I don't think ever happened in one of their many releases. Adding the metadata represented a bit of a challenge. We eventually had it generated from templates that would usually get filled out anyway.