Perhaps, I just checked it out now. The "substrs" themselves is not created by signing anything, created by the service? When posting creates kind 1 posts with a few non-standard tags such as "c" (which is supposed to be git commit id), "type" and "poll_results" Is Communities (it's like Reddit) not a better option, which is a standard NIP and it can be supported by multiple clients? Some clients has also started doing a new community type that is simply based upon a tag, while normal communities allow moderation and relay selection. Nostria will probably add support for that as well soon, so you can just choose "Moderated" or not. I don't think the "substrs" are published as Nostr events, so would need to create the "substrs" list using queries for events where people have posted in them, not very optimal. What is it you would like to see?