EVENTS in Classical ALV

Hi,

I want to know the Purpose of using the below Events in Classical ALV (if possible with example).

1. CALLER_EXIT

2. REPREP_SEL_MODIFY

3. top_of_coverpage

4. END_OF_COVERPAGE

5. TOP_OF_FOREIGN_PAGE

6. END_OF_FOREIGN_PAGE

7.SUBTOTAL_TEXT

Thanks in Advance,

Sumi