{qr} encodes its first parameter as a QR code and writes it as an inline SVG. The encoder is PAD's own (tags/_lib/qr.php): nothing is fetched and no image is stored, and the same text is always the same picture, so a page with a code caches and prints like any other.

The text is encoded in one mode - numeric for digits only, alphanumeric for upper case, digits and $%*+-./:, else the bytes of its UTF-8 - in the smallest of the 40 versions that holds it at the error correction asked, under the mask with the lowest penalty. A higher level survives more damage (a logo printed over it, a scratched label) at the cost of a denser code.

The colours are fixed, #000 on #fff unless color and background say otherwise - not following the page's dark mode, since a reader needs the contrast and a light quiet zone. The SVG has role="img" and the text (or title) as its name.

A text too long for version 40 at the level asked, or a level other than L, M, Q or H, is an error under the strict check, and the tag writes nothing. For a one-dimensional code on a product or a parcel see {barcode}.