For the curious, the ISO standard is ISO/IEC 14977. It is available here: https://standards.iso.org/ittf/PubliclyAvailableStandards/

Direct link to the standard: https://standards.iso.org/ittf/PubliclyAvailableStandards/s0...

But of course, as shanka commented, it isn't a standard that is followed practically. This is just a demonstration of https://xkcd.com/927/ in real life.