Not sure what you mean by real time scenario, I am guessing you meant real life scenario.
The documentation might be a bit confusing because it handles logical databases. But the event START-OF-SELECTION can also be used without that. It is the entry point of your program, i.e. after START-OF-SELECTION you put the code that does the actual work of your program. It can also be omitted since all code that is not in an event will be processed during START-OF-SELECTION, it is always wise to add START-OF-SELECTION however because otherwise you might get surprises when you add other events later.