3GPP 24.501 v20.0.0 — the document's own text
8.3.14.3 EAP message
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 external DN performs re-authentication and re-authorization of the UE using EAP and it completes unsuccessfully.