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

5.3.3.3.1 General

Taught in 9. Registration, reachability and paging (The 5G system architecture, in depth), 4. Knowing who you are and where you are (The 5G system architecture, overview).

NAS signalling connection management includes the functions of establishing and releasing a NAS signalling connection.