SAP ABAP PROCESSING BLOCKS documentation, setup help and example usage

ARTICLE

Reporting Events
Event key words for reporting events include:

INITIALIZATION ,

START-OF-SELECTION ,

GET node (obsolete, for logical databases only),

END-OF-SELECTION (obsolete, for logical databases only).

Reporting events occur in a predefined sequence and only in executable programs started using SUBMIT . In general, every executable program is implicitly started using SUBMIT . Only when a regular transaction code (not a reporting transaction) is used for the start (or external calls of their procedures), is a SUBMIT not triggered.
When an executable program is associated with a logical database , the assigned subroutine is executed in the database program before a reporting event is triggered.