Congratulations nostr:npub1zuuajd7u3sx8xu92yav9jwxpr839cs0kc3q6t56vd5u9q033xmhsk6c2uc , it is such a nice apps. 🎉 

I just wonder how you define the list of labels for topic. Is there any source/standard (ISO, Research Paper, etc.) that you have referred to define that? Happy to check and know that