Markus Kuhn’s International Standard Paper Sizes¹ is a great document on ISO-216 paper sizes, if you want a little more depth than HelloNurse’s succinct descrip

Markus Kuhn’s International Standard Paper Sizes¹ is a great document on ISO-216 paper sizes, if you want a little more depth than HelloNurse’s succinct description. It also covers US-style sizes toward the bottom. Kuhn also has an excellent ISO-8601 document², which makes you wish he would dive through more of the common standards that ISO stand guard over. ¹ https://www.cl.cam.ac.uk/~mgk25/iso-paper.html https://www.cl.cam.ac.uk/~mgk25/iso-paper.html ² https://www.cl.cam.ac.uk/~mgk25/iso-time.html https://www.cl.cam.ac.uk/~mgk25/iso-time.html - Sadly only covers timestamps, not durations/intervals/etc