Standards make life easier: they allow bank cards, for example, to fit into the slots provided worldwide. The DIN A4 format is probably the best known. It has been around for exactly 100 years. In 1922, the German Institute for Standardization (DIN) published standard 476 for paper formats. This guideline no longer exists, but the system does: thanks to the International Organization for Standardization (ISO), the DIN formats are now adapted almost everywhere in the world as ISO 216. There are now more than 24,500 ISO standards and around 34,000 DIN standards. Among them are some curiosities. Here are a few examples for World Standards Day (October 14):

Perennial favorite: The oldest DIN standard still in force is Guideline 1289 entitled "Firebox for tiled stoves; filling door for filling firing". It was published 94 years ago. This was in 1928 and deals with the construction and closure of the door on tiled stoves. Incidentally, DIN 1 was the first standard ever to be published in March 1918. It defined the dimensions of tapered pins used in mechanical engineering. It was valid for more than 84 years and was replaced by the European standard DIN EN 22339 in October 1992.

Brewed: One of the most unusual standards is ISO 3103, which deals with the question of how to make a perfect cup of tea. The size, material and shape of the teapot, proportion of water, brewing time and pouring the milk are defined on six pages. First published in 1980 and revised in 2019, the ISO standard was awarded an "Ig Nobel Prize" in 1999 - pronounced "ignoble", which translates roughly as "dishonorable". It is awarded annually at Harvard University to honor curious research.

When a goal is scored: On April 1st of all days, a goal was scored before the soccer match started. During Real Madrid's match against Borussia Dortmund in the Champions League, the corner collapsed even though the ball was not yet in play. That was at 8.44 pm on April 1, 1998, around 60 seconds before the actual kick-off. It took 76 minutes for a substitute goal to be installed. For Günther Jauch and Marcel Reif, the incident was a great moment of moderation, but also a clear violation of DIN EN 748, the European standard that specifies requirements for the stability of the goals, the stability of the crossbars, the strength of the foundations and the tear resistance of the goal net.

Toast: ISO standard 3591 has defined the manufacture of a glass for wine tasting since 1977. The standard defines such a wine glass as a cup that is described as an "elongated egg". This is "supported by a stem resting on a base". It also states that the opening of the cup is "narrower than the convex part in order to concentrate the bouquet". The standard also describes other characteristics and gives recommendations for use.

Well brushed: Those who follow their dentist's advice will benefit from it at least twice a day. The tuft extraction test ensures that each individual small tuft of a toothbrush can withstand a force of at least 15 Newtons in accordance with the international standard DIN EN ISO 20126. For comparison: the average compressive force in a man's entire hand is around 500 Newtons. Thanks to the standard, the tufts should remain in the brush head and not be swallowed up. According to the German Institute for Standardization, this works well in practice. Because before bristles fall out, they are usually so bent that the user prefers to use a new toothbrush.

In harmony: not all standards are about tangible things. Thanks to ISO standard 16, a visit to an orchestra is usually a treat for the ears. However, if this is not the case, the violinist may not have complied with an international guideline. ISO standard 16 sets the pitch of note A at 440 hertz. Tuning forks and electronic tuners are set to this pitch.

The standard of standards: There is also a standard for the standards themselves. With around 34,000 DIN standards, this is no longer a surprise. The DIN 820-1 guideline specifies the criteria that must be met when awarding standards. Under "General principles", it states that standardization should serve the "safety of people and property as well as the improvement of quality in all areas of life" and should "not lead to a special economic advantage for individuals".