[barongreenback]

Thanks for the replies. I was worried I'd mess up the terminology somewhere and cause some confusion and I now see the problem with my first sentence. Luckily, just as I can usually understand my cat, BruceZ seems to know what I'm talking about. The link is just what I'm after. Also, it was Jason1990's posts I remembered.

Was my use of 'SD of my SD' also incorrect?

I'm going to need several lifetimes to do all the study that I want to do.<sigh>

Thanks again,
James