A lurker comes out of hiding

Welcome, NC. Glad you decided, (as someone said)"delurk". I don't think I have to tell you anything about the place. You're probably got the gist of it by now.Don't hold back on posting though. Sometimes if you are not an expert in a field you can see where someone else is having a struggle with the explanation an expert is giving. They tend to forget how the rest of us know.