Here we will start a list of frequently asked questions and their answers that don't belong on the general forum.

• How are "on change of" and "at end of" different?
  
  
  
  • Event block "ON CHANGE OF" is now one of obsolete ABAP constructs. That's how it works: when execution reaches "on change of" the variable of question is compared with another hidden variable of the same type. And if the comparison failed then the block between ON and ENDON is executed and new value of the variable is stored in the hidden variable. Thus you can see that ON CHANGE OF always works at first comparison but the only case when the compared variable has initial value.

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  • AT END OF event block can only be used inside LOOPs, moreover you should not use it in LOOPs which have WHERE clause or the result will be unpredictable. Before use AT END OF (or AT NEW) make sure your internal table is sorted. AT END OF will work at the end of contiguos sequence of table records with the same value of field in question. But note that AT END OF will also work if any of the fields to the left has changed its value.

• Also:
  
  
  
  • AT FIRST works at the very first loop pass, and AT LAST works at the last loop pass.
  http://it.toolbox.com/wiki/index.php/ABAP_Documentation_for_Newbies