 A lot of care was needed to set out a page for writing and illuminating in medieval manuscripts because guidelines were needed to indicate where lines started and ended, where the page started and ended, and indeed whether there were going to be any inserts for allowing larger initials in margins. Here I'm using metal dividers to indicate the markings on the page. These are like compasses used in school but there's a point at each end rather than a point and a lead point. I'm setting out the margins of the text block here and now I've reset the dividers so that they're marking out the positions of each line. This was traditionally done at either side of the page so it was quite easy for a straight edge to be placed such that the dots could be joined up and the lines were parallel. And now the page is ready for writing. Manuscript books were almost invariably made by having the pages flat. It's much easier to work flat and it's certainly much easier to mark out the lines and the text blocks when a page is flat than in a bound book.