# Numbering

DIN 6763
Area Numbering
title Numbering; Basic concepts
Brief description: Forming, issuing, managing and using numbers
Latest edition 1985-12
ISO

Under Numbering the "forming, issuing, managing and applying numbers" is meant for Nummerungsobjekte ( DIN 6763). Numbering objects in the sense of this definition can be objects, data carriers, persons or facts. A number in the sense of numbering is a defined sequence of characters such as letters, digits and special characters. In data processing , the term key is used for number and number allocation is also called key selection, key allocation or, more rarely, encryption (which can, however, be confused with encryption of cryptography ). The DIN standard was revised in 1985 and now defines various terms differently. In other respects, too, various terms are sometimes used synonymously, but sometimes not always congruent.

In electronic data processing , key allocation / key selection is of great importance in data modeling of objects and their relationships, especially as database keys . Identifying keys are also used in various data structures , e.g. B. in the associative data field .

## Numbering system

A number system is the description and explanation of the appropriate structure and summary of numbers or number parts (according to DIN). As a rule, the numbering systems or the numbering system parts are divided into “systematic” / “system-free” and “not speaking” / “halfway” / “fully compliant”.

• Systematically
• not speaking: identifying number
A numbering object is identified if it can be clearly identified, designated or addressed using its number (based on DIN 6763). The simplest form of an identifier is a consecutive counting number or numbering , but there are also more complex numbers such as globally unique identifiers . The identifying key does not normally allow any conclusions to be drawn about the object in question.
• compliant: classifying number
Classifies or arranges the objects to be labeled according to specified criteria in classes or groups and can consist of several parts. The parts can be linked or hierarchical or independent. Talking key . The advantage of speaking numbers is that they are easy to remember, which makes it easier to work with them. The disadvantage is that the number is usually long, which means that it is very difficult to record and maintain and the risk of “bursting” ( overflow ), if this is not foreseeable or not Foreseen aspects require an extension or if the counting number which determines the uniqueness was chosen too small. Examples are school grades or material groups .
In the case of objects with a large number of variants, the "characteristics" of the object are used as classifying numbers; two forms of classification have emerged:
• the feature-related numbering in which the features are loosely next to each other
• the logical numbering in which the characteristics form a Boolean group:
• half-way: compound number (or hierarchical compound number)
Consists of the classifying and identifying component, the identifying part always being dependent on the classifying part. Both components are necessary for the clear identification of an object. Example German license plates : The first 1–3 letters for city or district are the classifying part, the rest the identifying part. The advantage is the small number of digits, but there is a major disadvantage in the poor expandability of the classifying part because it is also used for identification.
• System-free: parallel number (or non-hierarchical group number)
Consists of at least two independently systematic number systems, mostly of a classifying and identifying component. The object is clearly identified by the identifying part, the classifying part is independent of it and describes the object. Parallel numbering systems have some key advantages: they can grow indefinitely; the classification of different characteristics is independent of other characteristics; therefore features that have become meaningless due to technical development can simply be omitted or no longer maintained, while new aspects can be taken into account by additional number parts.

## Numbering plan

The numbering plan is an overview of the previously defined meanings of classifying number parts (according to DIN). There are hierarchical (decimal) and secondary (decimal) numbering plans. The “DK” numbering plan is an example of a decimal classification . In the case of a subordinate number plan, the classes of the individual positions can be linked with one another as required. The numbering of part families according to Opitz is an example of a combination of hierarchical and secondary elements of a numbering plan.

A numbering scheme is the representation of the formal structure of the numbers and their spelling.

## literature

• B. Grupp: Optimal encryption for online data processing - construction of modern numbering systems for part numbers of all kinds, personal numbers and order numbers . TÜV Rheinland Verlag, Cologne 1987.
• Herlyn: PPS in the automotive industry - production program planning and control of vehicles and assemblies . Hanser Verlag, Munich 2012, ISBN 978-3-446-41370-2 .