3GPP 23.501 v20.2.0 — the document's own text

5.17.4 Network sharing support and interworking between EPS and 5GS

Taught in 19. Living next to 4G (The 5G system architecture, in depth), 7. Roaming, other accesses, the edge and the outside (The 5G system architecture, overview).

The detailed description for supporting network sharing and interworking between EPS and 5GS is described in clauses 4.11.1.2.1, 4.11.1.2.2, 4.11.1.3.2 and 4.11.1.3.3 of TS 23.502 [3].