What fields need to change in F4301 & F4311 to trigger RTPOOUT

I've found plenty of documentation on the Real Time Event RTPOOUT. The documentation says that the RTE is trigger if a purchase order is created or updated. However, I know from experience that it is only triggered if certain fields are changed. For example, just changing the Reference field doesn't trigger an RTE. However, I know a status update will trigger an RTE. Does anyone know what are the fields which when changed will trigger an RTE? Or does it require a status update? Does anyone know how I can find out? Other than sitting there and changing each field,