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ABAP Keyword Documentation → ABAP − Reference → User Dialogs → Messages → Behavior of messages →Messages in List Processing
During list processing, a message of type "W" is always converted to type "E" before further context-dependent handling takes place. The message is then handled in accordance with the other context.
List processing is active in the following contexts with respect to messages:
In programs called using SUBMIT, list processing is active, therefore, apart from when actual list events are being handled (even when reporting events are being handled). This is especially true for the standard event START-OF-SELECTION.
Note
Background jobs are always started using SUBMIT, which means that list processing is usually also active at the same time.