3GPP 23.501 v20.2.0 — the document's own text
4.4.6.2 Reference points to support 5G LAN-type service
Taught in 21. Emergency calls, messages, voice and location (The 5G system architecture, in depth).
N19: Reference point between two UPFs for direct routing of traffic between different PDU Sessions without using N6. It has a per 5G VN group granularity.