Are any of the other NIPs mandatory? I don’t think so, but I did not search very long.

We agree that there should be as few *mandatory* NIPs as possible. I honestly think Nostr is doing this right—a minimal base of mandatory NIPs plus whatever optional features that clients and relays choose.

I like that different clients have compatible features. How do we accomplish this without additional NIPs? (This is not a gotcha. I am sincerely open to other ideas.)