One code per page. Take the SVG for anything large — a poster or a door sign — and the PNG for a document or a slide. The card PDF is a ready-made page: the code, what the page does, and the address typed out underneath.
Printing a code Keep it at least 25mm across, never crop the white margin around it, and print black on white. The address is under every code on purpose: a reader with a broken camera types it.
