There's been some confusion about the concept of "targets" in Operations Manager 2007. If you're familiar with object-oriented modeling or programming, you can think of a target as a class. In more general terms, targets are how you tell Operations Manager what objects rules should apply to. For a great four-minute overview and demo of targeting, see the targeting video available on Technet.
Speaking of targeting, what sorts of questions do you have about targeting? I'll run a short series about the concept and answer your questions there.
It is a question concerning scope.
On what condition is the class of "Common target" decided?