"Ok, so say I need you to go and put this note of death at the end of the Mason file; that would be the 20th folder. You go to the drawer, count up to 19 from the first Mason folder and put the note there. You just ended up declaring Mr. Moriarty dead. Mr. Łeldon here will be processing credit card applications later in the afternoon; I'm pretty sure that Mr. Moriarty isn't going to get his now.

This is the way one uses the 'buffer overflow' problem in computers to manipulate data. With a little skill you can use it to do serious damage. Consider, for instance, what would happen if we were at an engineering company and slipped in a new blueprint for a machine instead of a personell note. Later someone else would pick up the design and the factory, none the wiser, would proceed to build our machine, instead of the one they wanted.