3GPP St  Application ( 16777349 )

St is used to provision the traffic steering control information from the Policy and Charging Rule Function (PCRF) to the Traffic Steering Support Function (TSSF). The TSSF is the control plane part of the TDF (without the TDF charging related aspects), providing classification control.
Reference:  3GPP TS29.212   View
MESSAGES

Name

Code

Session-Termination-Request St 275
Session-Termination-Answer St 275
TDF-Session-Request St 8388637
TDF-Session-Answer St 8388637
TSSF-Notification-Request 8388731
TSSF-Notification-Answer 8388731