You can generate events as follows:
To generate a custom event handler: you have to create an operation and set a value to the EventID extended attribute
To generate a standard event handler: you have to create an operation and select an event value in the Language Event list in the operation property sheet
To generate a user-defined event handler: you have to create an operation and select the <<event>> stereotype. The Language Event list must remain empty
When the EventID extended attribute has a value, the operation is generated as a custom event handler, although it has a name defined in the Language Event list or the <<event>> stereotype.