International standardization

Standards are agreements between various actors, such as manufacturers, operating companies, inspection bodies, authorities, etc. – they are not developed and adopted by governments or other state agencies. They therefore have no immediate legal implications, but describe the state of the art at the time of their completion.
Standards can be applicable internationally (ISO, IEC), regionally (e.g. European) or nationally (e.g. DIN, SN, NF, BS, etc.). For historical reasons, there are purely national, purely European and international standards. It is often the case that international standards are adopted regionally as EN ISO xxxxx or EN IEC 6xxxx, and nationally e.g. in Germany as DIN EN ISO xxxxx and DIN IEC 6xxxx. 
Standards can be developed as an international standard from the outset or originate from regional standards (usually under a new number with partially new content).

In the machine safety area, the following bodies are relevant as internationally active standardization organizations:

	ISO (International Standardization Organization) – publishes standards for primarily non-electrical technologies
	IEC (International Electrotechnical Commission) – publishes standards for electrical engineering and electronics, telecommunications, energy production and distribution as well as other electrotechnology-based technologies.

The equivalent organizations on a European level are:

	CEN (Comité Européen de Normalisation) – develops and publishes its own European standards (EN) and adopts ISO standards as European standards
	CENELEC (Comité Européen de Normalisation Electrotechnique) – develops and publishes its own European standards (EN) and adopts IEC standards as European standards

Apart from the standards, there are additional information documents issued by ISO and IEC:

• TS – Technical Specification. Often as a kind of pre-standard (e.g. IEC/TS 62046)
• TR – Technical Report. Often contains supplementary information that relates to a standard and represents the state of the art (e.g. ISO/TR 24119)

In addition to the adopted standards that have the status "International Standard", there are also preliminary stages in the standards development process, e.g.

• CD (Committee Draft) – working version for comments by national standardization committees
• DIS (Draft International Standard) – intermediate version for public comments
• FDIS (Final Draft International Standard) – final version shortly before adoption

Even if standards with this status are not yet normative, they indicate the state of the art and, considering the many years it takes for a standard to be developed, are of interest as an intermediate stage for future users and other standards maintenance groups.

Standards classification system

ISO and IEC as well as CEN and CENELEC use the following classification system for machine safety standards:

Type A standards
Basic safety standards for a specific field, e.g. ISO 12100 for machine safety, IEC 61508 for programmable safety controls

Type B standards 
Safety group standards for specific safety aspects (B1) and specific safety devices (B2) that refer to type A standards

Type C standards
Machine-specific safety standards that refer to type B and type A standards

As a general rule, if deviating requirements exist in differently classified standards, type C standards have priority over type B standards and these in turn have priority over type A standards.

Below is an overview showing a selection of key international standards (without specification of year):

Type C standards that specifically apply to Europe (EN standards) can be found here:

European standards