And with civil servants hard-hit by the latest round of austerity cuts, working to rule has become the norm.

Setting it to true ensures that when a rule updates the knowledge in the working memory, you don't end up with rules being reevaluated and reexecuted, which could then cause an infinite recursion.

In the past, music and movie fatcats were able to figure out the unwritten rule that McGraw so glibly overlooked: If you're working with Apple, shut up about it until Steve has left the stage.