From Douglas Adams:
"But Mr. Dent, the plans have been available in the local planning office for the last nine months."
"Oh yes, well, as soon as I heard I went straight round to see them, yesterday afternoon. You hadn't exactly gone out of your way to call attention to them, had you? I mean, like actually telling anybody or anything."
"But the plans were on display ..."
"On display? I eventually had to go down to the cellar to find them."
"That's the display department."
"With a torch."
"Ah, well, the lights had probably gone."
"So had the stairs."
"But look, you found the notice, didn't you?"
"Yes," said Arthur, "yes I did. It was on display in the bottom of a locked filing cabinet stuck in a disused lavatory with a sign on the door saying 'Beware of the Leopard'."
Exempli gratia, from a discussion on FurryMUCK:
Leonard proposed The Rules Lawyer's Maxim: Where there is no Text, there is an Argument.
normanrafferty countered with Rafferty's Extension to the Rules Lawyer's Maxim: Stopping at the end of the line and not cross-referencing is NOT a lack of text.
Your Obedient Serpent responded with athelind's Commentary on Rafferty's Extension to the Rules Lawyer's Maxim: If you can't FIND the rule, you don't HAVE the rule. Lack of cross-referencing IS a lack of text.
The Beware of the Leopard school of game design scatters vital rules for important situations -- say, combat -- all over the rulebook, with neither repetition for emphasis nor cross-reference. If important rules appear in the Index, you will only be able to find them if you know in advance what specific game-jargon term the system uses -- and that term will only be used in the Index and in the single obscure entry that's a footnote to a seldom-used table in the back of the book.
This is in no way a reference to actual leopards.