QR codes and short links

Every short link carries its source, so a code on a door and a code in a mailer are two different lines in reporting even when they point at the same page.

• Create the link first, then generate the code from it. The code encodes the short link, so you can repoint the destination later without reprinting anything.
• Give each placement its own link. One code for everything answers no question worth asking.
• Print at a size where the code survives being photographed at an angle in bad light.