What is the meaning of "Clients MUST NOT multiplex XMPP streams over the same WebSocket" (from RFC 7395 § 3.4)?

Question

While I was reading the RFC 7395. I read this statement

From Section 3.4. Stream Initiation Page 6

Clients MUST NOT multiplex XMPP streams over the same WebSocket.

I have questions

What is multiplex XMPP streams?

Why Clients MUST NOT multiplex XMPP streams over the same WebSocket?

Answer 1

It means that you must not use multiple XMPP streams over the same WebSocket. If this was allowed then you could use 2 or more streams over the same WebSocket, e.g. allowing you to authenticate and use 2 or more XMPP sessions over the same WebSocket.