nostranoobus on Nostr: What does '#[0]' at the beginning of your message mean? Does that refer to a user on ...

What does '

quoting nevent1q…9xg6

#[0] is there a char limit for the posts? feels like i can write an entire essay into this box; but idont want to clog

' at the beginning of your message mean? Does that refer to a user on other clients?