Expressions in ISO International Standards

Users of ISO International Standards and other normative ISO deliverables [Technical Specifications (TS), Publicly Available Specifications (PAS), International Workshop Agreements (IWA) may wish to update on the use of expressions commonly used in the world of standardisation.

The  following definitions apply in understanding how to implement an ISO International Standard and other  normative ISO deliverables (TS, PAS, IWA).

  • “shall” indicates a requirement
  • “should” indicates a recommendation
  • “may” is used to indicate that something is permitted
  • “can” is used to indicate that something is possible, for example, that an organization or individual is able  to do something

In 3.3.1 of the ISO/IEC Directives, Part 2 (sixth edition,  2011) defines a requirement as an “expression in the content of a document  conveying criteria to be fulfilled if compliance with the document is to be claimed and from which no  deviation is permitted.”

In 3.3.2 of the ISO/IEC Directives, Part 2 (sixth  edition, 2011) defines a recommendation as an “expression in the content of a document  conveying that among several possibilities one is recommended as particularly suitable, without mentioning  or excluding others, or that a certain course of action is preferred but not necessarily required, or  that (in the negative form) a certain possibility or course of action is deprecated but not prohibited.”

Implications for conformity  assessment
Conformity assessment is the demonstration  that specified requirements relating to a product, process, service, person, system  or body are fulfilled.

Demonstration of specified requirements  may be undertaken by a manufacturer or supplier (first party), a user or purchaser (second party), or  an independent body (third party).

Pursuant to 6.7 of the ISO/IEC Directives,  Part 2 (sixth edition, 2011), ISO International Standards and other normative ISO deliverables (TS,  PAS, IWA) that contain requirements are written in accordance with the “neutrality  principle”, such that conformity can be assessed by a first party, second party, or third-party.

ISO  International Standards and other normative ISO deliverables (TS, PAS, IWA) that do not contain requirements  (i.e. do not contain the verbal expression ‘shall’) are not intended to be used for conformity assessment.

The original text can be found on the ISO website at http://bit.ly/1e5a2Ju

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