Denver Greg

Hello all, This is my first post and rather that starting a new thread I'm reviving this one...anyway I acquired a Beattie screen for my RB67 Pro S on eBay and would like to know more about the one I got being I can't find ANY info on this particular one. According to the case it came in ( assuming it's the right case ) it's a Lifetouch Grid Beattie number 83301 and I know it's gridded for 6x7 and 645 but what are the additional lines for? I'm assuming the small rectangle is for framing vertical portraits or is it for something else? If you are familiar with this screens uses I'd love to know more. Thanks!