It’s a size of paper with an aspect ratio of 1:√2, and the short edge that is 21cm long. The long edge will then be 21√2 = 29.7cm. The aspect ratio has the interesting property that it can be halved and doubled while remaining constant.
This has been your ISO fact of the day.
ISO 7304-2:2008 defines a standard for cooking spaghetti. Subsection 3.9 “Completeness” closely resembles “al denté” but isn’t true al denté; as 3.9 states “no white core visible” when a noodle is inspected crosswise with a razor blade. Al denté phase is sensed via the teeth for texture differential of the inner and outer part of a spaghetti. No agreement has been reached by international consortium of Italian food preparers and dentists as to which tooth is to be used. Thus, the standard must be reviewed every 5 years by sensory analysis.
