ISO 2848 is an ISO standard used by the construction industry. It is based on multiples of 300 mm and 600 mm The numbers 300 and 600 were chosen because they are preferred numbers due to their large number of divisors – any multiple can be evenly divided into 2, 3, 4, 5, 6, 10, 12, 15, 20, 25, 30, etc., making them easy to use in mental arithmetic. This system is known as "modular coordination". A related standard is British Standard 6750.
Basic module
The standard unit of ISO 2848 is a basic module, a length of which is represented in the standards by the letter M. Adherence to the standard means that major dimensions such as grid lines on drawings, distances between wall centres or surfaces, widths of shelves and kitchen components are multiples of the basic module. As dimensions increase, preference is given to lengths which are multiples of 3, 6, 12, 15, 30 and 60 basic modules. For smaller dimensions, the submodular increments M and M are preferred.
A metric foot is a nickname for the preferred number length of 3 basic modules, or. The 300 mm metric rule is of a similar length to the traditional imperial one-foot rule. A metric foot is shorter than an imperial foot. Although the term "metric foot" is still occasionally used in the United Kingdom, in particular in the timber trade, dimensions are most likely to be quoted exclusively in metric units today. The sizes of the studios at BBC Television Centre in London, which opened in 1960, are specified and measured in metric feet, in contrast to film stages where imperial feet and inches prevail.
A metric inch is a nickname for a preferred subdivision of an ISO 2848 basic module, or of a metric foot measuring. A metric inch is shorter than an inch, since the inch is defined as 25.4 millimetres. The term was similarly used to refer to the historical Soviet Bloc practice of spacing integrated circuitpins at of a 25 mm "metric inch" length, instead of the Western practice of of an imperial inch.
