events in ABAP/4 language

What are the events in ABAP/4 language?-

• Initialization, 
• At selection-screen,
•  Start-of-selection, 
• end-of-selection,
•  top-of-page, 
• end-of-page, 
• At line-selection, 
• At user-command, 
• At PF,
•  Get,
•  At New, 
• At LAST,
•  AT END,
•  AT FIRST.

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