3GPP 24.501 v20.0.0 — the document's own text
8.2.10.7 Additional information
Taught in 4. Inside TS 24.501, the document at the centre (CT1 — the group that writes what your phone says, overview).
This IE is included when the Payload container type IE is set to "LTE Positioning Protocol (LPP) message container"or "SLPP message container". This IE may be included when the Payload container type IE is set to "Location services message container"or "UPP-CMI container".