Events – PB Docs 2022

Most system events return a value. The return value is a long
numeric codes have specific meanings for each event. You specify the
event’s return code with a RETURN statement in the event script.

When the event is triggered by user actions or system messages,
the value is returned to the system, not to a script you write.

When you trigger a system or user-defined event, the return value
is returned to your script and you can use the value as appropriate. If
you post an event, you cannot use its return value.