3GPP 24.501 v20.0.0 — the document's own text
8.2.6.39 Requested T3512 value
Taught in 4. Inside TS 24.501, the document at the centre (CT1 — the group that writes what your phone says, overview).
The UE may include this IE during the registration procedure if it requests to use MICO mode and T3324 IE is included, to request a particular T3512 timer value.