A technical standard is an established norm or requirement in regard to technical systems. It is usually a formal document that establishes uniform engineering or technical criteria, methods, processes and practices. In contrast, a custom, convention, company product, corporate standard, etc. that becomes generally accepted and dominant is often called a de facto standard. A technical standard can also be a controlled artifact or similar formal means used for calibration. Reference standards and certified reference materials have an assigned value by direct comparison with a reference base. A primary standard is a technical standard which is not subordinate to any other standard but serves to define the property in question. Primary standards are usually kept in the custody of a national standards body. A hierarchy of secondary, tertiary, and check standards are calibrated by comparison to the primary standard; only those on the lowest level are used for actual measurement work in a metrology system. A key requirement in this case is traceability, an unbroken paper trail of calibrations back to the primary standard. This video is targeted to blind users. Attribution: Article text available under CC-BY-SA Creative Commons image source in video

• published: 16 Oct 2015
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