Anno the bell (audiable ASCII character) was ^G (Ctrl+G)

I think it could be \b

Sorry, this one escaped onto the network, was meant to be local only (and this is a broken example). Reviewing https://github.com/nostr-protocol/nips/pull/635 to see what we should do for escaping control characters other than /n and ", such as the bell character (\b or 0x07).