Below are some important events in ABAP programming:
LOAD-OF-PROGRAM : This is the first event to be called before any of the other ABAP code is processed.
INITIALIZATION : It is called after the ABAP selection screen code has been processed. This event is used to initialize input fields of the selection screen or change the default values of these.
AT SELECTION-SCREEN OUTPUT : This event is called just before the selection screen is displayed. It can be used to manipulate the actual selection screen attributes using the loop at screen functionality. This event allows functionality like hiding fields, grey them out, so they are output only or make them intensified, etc.
TOP-OF-PAGE : This event is called when a new page is started with an ABAP list. It is used to display a header for the list.
TOP-OF-PAGE During LINE_SELECTION : This event is also activated while creating detailed lists.
END-OF-PAGE : This event is displayed at the end of each page.
