GetUserDefinedEventNumber() NWScript command retrieves the integer identifying an OnUserDefined event. This is the number used to create the event with EventUserDefined(), and its meaning is completely determined by the person writing the scripts. However, the numbers 1000 through 1011, 1510, and 1511 are used by BioWare to indicate standard events that have been requested to signal a user-defined event, and accepting this meaning of these particular numbers is good scripting practice. See SetSpawnInCondition().
int GetUserDefinedEventNumber (
This should only be used in an OnUserDefined event.