Steve,
Ed Rauh answered your question in detail, so I won't repeat. I do want to say (to you and by extension to everyone else on UT) that you should ALWAYS say when you don't understand something. After all each of us had to learn this stuff too. And probably were as confused at first as you!

Barbara


>This had me confused from day one of these kinds of discussions and I finally worked up the guts to say I don't get it!
>
>--Steve.