<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div><blockquote type="cite"><span class="Apple-style-span" style="border-collapse: separate; font-family: Helvetica; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; ">I am certain that one interactive run-through with said page will help you<br>understand the principles, although I think they should have estimated 20<br>minutes for the little course, not 15.<br></span></blockquote></div><br><div>OK, thank you Johannes and Curtis. So now you see I wasn't kidding when I said I was confused! ;-) Clearly I need to read and study a bit! Believe it or not, your explanations are helping, and it is starting to come together for me -- before asking these questions I had no idea how to unravel this mystery, now I do! Thanks again.</div><div><br></div><div>Chris</div></body></html>