The fellow who designed it, is working far away;
The spec’s not been updated for many a live-long day.
The guy who implemented it, is promoted up the line;
And some of the enhancements didn’t match to the design.
They haven’t kept the flowcharts, the manual is a mess;
And most of what you need to know, you’ll simply have to guess.

by David Diamond

Update: This is dated June 1976, by the way.