@ralphm Going back Slack/Discord use cases, one can react to an old message (ej. for role bots) or use emojis as a way to run informal polls. So they might need to refer to an old message, that requires message IDs, which bring in state to be kept on the server side. #xmpp already has that concept from what I can see in the blog, stanza-id. Does the XML parsing requirements of xmpp make use of XML namespaces?