I wonder if that could get registered for this purpose somehow?

Ports get registered? I just assumed we were all picking whatever open ports we could find.

Way back in the idealistic days of the internet you could apply for and reserve a port for your protocol.

I don't think you can do this anymore..., or if you can it's not easy.

Sometimes in Port Forwarding wizards on routers, you see a big list of ancient videogames. Presumably that has something to do with this.