NIP-35?
Discussion
The numbers aren't assigned sequentially, so some are missing.
You can see the full list here:
https://wikifreedia.xyz/nip-event-register/dd664d5e4016433a8c
good to know, will you also be the undocumented type?
What do you mean?
this site https://undocumented.nostrkinds.info/
Oh, that's useful input, thanks! Bookmarked it.