My thanks to all who pitched in to help.
I think I understand the answers to my question. I still need to think about where the "\2" fits in (I understand, not in this case).
I've bookmarked the tutorial sites and will study these and then probably buy RegexBuddy;
Again thanks. Regards - John
P.S. The ranks of those who have worked with the PDP-8 are starting to thin. I haven't fiddled with one for almost fifty years. Ye gods! That makes me feel old.