Charles Pergiel sent this over from a Chromebook forum, and the truth of it hurts just a little:
I remember my early days with computers, asking a question of the developers of a fairly large (for 1980) piece of IBM mainframe software, and their response was “*We don’t know*.” At the time, I found this unbelievable *you guys wrote it; why don’t you know how it works!?*”
Things have gotten more complicated by orders of magnitude since then, and sometimes the only reasonable answer is “We don’t know.”
I was working on an IBM mainframe in those days, and I can assure you that this wasn’t at all a unique situation: a lot of legacy stuff outlived its original developer, and subsequent developers opted, quite reasonably, to leave well enough alone.