With option SUMMARY defined in UCONF:
xfb.transfer._value_       = SUMMARY

What are events sent to Sentinel?

With option SUMMARY,  for each transfer,  2 events are sent to Sentinel, one for the initial step and another for final step.

Here are details:

- Requster/sender side (command SEND):
event with state TO_EXECUTE
event with state SENT

- Server/receiver side (without transfer command):
event with state RECEIVING
event with state RECEIVED

- Server/sender side (command  SEND STATE=HOLD) :
event with state  AVAILABLE
event with state  SENT

- Requester/receiver side (command RECV):
event with state TO_EXECUTE
event with state RECEIVED