The first is a persistent demand shock -- for example, an increase in aggregate demand that results in a persistent departure from trend growth and persistent changes in utilization rates. This will have symmetric effects, raising both output and inflation, and presents a relatively straightforward monetary policy problem that is well handled by the first set of rules.
A second source of shock is a supply shock, an example of which would be a one-time, permanent increase in oil prices. We have had several examples of very sharp increases in oil prices, especially in the 1970s, and, more recently, oil prices have been declining since the end of 1996.