Ditto. Data structures is pretty much the only subject I have referred back to.

P.S. Rule #7 is important, but when it gets broken its a good way to discover lots of dirty little secrets. The last time I broke this rule I discovered that the automated setup scripts we had weren't ever actually being run - instead the nerds were copying chunks of SQL out of the scripts and applying them by hand. Of course it turns that that the scripts didn't work (fancy that).