I'm sure this is an obvious question but after much tinkering all I've managed to do is confuse myself.
I'm typesetting a book. The paper size is 5.5×8.5". I want to apply the canons of page construction to the book. If I calculate 1/9 of 5.5×8.5" I get a fundamental grid size of 0.611×0.944", which leads me to a text width of 6 × 0.611" = 3⅔" and a text height of 6 × 0.944" = 5⅔". To effect this, I need to set the backspace and topspace to one grid unit, so backspace = 0.611" and topspace = 0.944". The first thing that confuses me is that the text area should be 6 × 6 grid units, but the text area computed by the canon does not include the headers and footers (is this correct?). The canon doesn't really tell you what to do about headers and footers. Assuming I pick some random size, what's the right way to configure
The document Help! The typesetting area is helpful, but I couldn't find the Metapost program mentioned which does the calculations for a given paper size. The paper mentions additionally that ConTeXt would soon provide default page setups based on ninths-division, but I don't know if that ever became true (the document is from 2004) or if it did, where they are and how to use them. Obviously if I can avoid hard-coding these things into my document by using pre-defined setups, or at least, calculations in my own document, it would be better.
Thanks for your help!