3GPP 23.501 v20.2.0 — the document's own text
5.7.7.4 PDU Set Integrated Handling Information
Taught in 14. What the network promises (The 5G system architecture, in depth), 23. Very fast, very reliable, very picky (The 5G system architecture, in depth), 5. The connection, and what is promised on it (The 5G system architecture, overview).
The PDU Set Integrated Handling Information (PSIHI) indicates whether all PDUs of the PDU Set are needed for the usage of the PDU Set by the application layer in the receiver side. PSIHI is an optional parameter. A QoS Flow is associated with at most one PSIHI value per direction.