3GPP 24.501 v20.0.0 — the document's own text
8.2.19.24 Truncated 5G-S-TMSI configuration
Taught in 4. Inside TS 24.501, the document at the centre (CT1 — the group that writes what your phone says, overview).
This IE may be included to provide a new truncated 5G-S-TMSI configuration to the UE in NB-N1 mode if the network is configured to provide the truncated 5G-S-TMSI configuration for control plane CIoT 5GS optimizations.