PD 6461-1:1995 Vocabulary of metrology - Part 1. Basic and general terms (international)
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This Published Document reproduces verbatim the International vocabulary of basic and general terms in metrology (VIM) published by ISO. It supersedes PD6461-1:1985 which is withdrawn. The parts of PD6461 are published as follows: — Part1: Basic and general terms (VIM); — Part2: Vocabulary of legal metrology (VLM); — Part3: Guide to the expression of uncertainty in measurement (GUM). The UK participation in its preparation was entrusted to Technical Committee SS/7, General metrology, quantities, units and symbols, which has the responsibility to: A list of organizations represented on this committee can be obtained on request to its secretary. It is emphasized that the VIM does not of itself have the status of a British Standard. However, definitions of fundamental terms applicable to all aspects ofmetrology are contained in BS5233 Glossary of terms used in metrology (incorporating BS2643), which are essentially identical with those given in the VIM. A new edition of BS5233 is currently in preparation. For historical reasons, Part2 currently contains many basic metrological terms in addition to those of mainly legal application. Where any conflict exists between the definitions in Part2 and those from Part1 (i.e.from the VIM) the later should be regarded as authoritative. When the International Organization of Legal Metrology (OIML) revises the Vocabulary of legal metrology a new edition of PD6461-2 will be published. In order to expedite publication and for ease of reproduction, the text of the VIM has been used as the basis of this Published Document (PD). However, it should be noted that dissatisfaction has been expressed over the definition of the term “uncertainty of measurement” (term no. 3.9) as it fails to express the meaning that is needed and is, moreover, very different from all existing and previous definitions of the term. The VIM definition of the “uncertainty of measurement” is taken from the ISO Guide to the expression of uncertainty in measurement and represents the views of some members of the ISO Working Group (ISO/TAG4/WG3) that produced the guide. These experts disliked the concept of “true value” as this value cannot be stated exactly. Many other people consider that the definition is incorrect as it is imprecise (i.e.what is the “dispersion” from?). It implies that “uncertainty” is only relevant if several measurements are made, and it fails (by not mentioning “true value”) to invoke the concept of traceability. It is considered that the following definition more exactly meets the requirements of metrological accreditation services and industrial metrologists.
