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Foreword - Supplementary information

A link to the following text is included in the foreword to all ISO standards and other deliverables. These explanations are designed to help standards writers and users understand the application and context of ISO standards.

Expressions in ISO International Standards and other normative ISO deliverables [Technical Specifications (TS), Publicly Available Specifications (PAS), International Workshop Agreements (IWA)]

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 the ISO/IEC Directives, Part 2, Seventh edition, 2016, 3.3.3, a requirement is defined as an "expression in the content of a document conveying objectively verifiable criteria to be fulfilled and from which no deviation is permitted if compliance with the document is to be claimed."

In the ISO/IEC Directives, Part 2, Seventh edition, 2016, 3.3.4, a recommendation is defined as an "expression in the content of a document conveying a suggested possible choice or course of action deemed to be particularly suitable without necessarily mentioning or excluding others."

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 the ISO/IEC Directives, Part 2, Seventh edition, 2016, Clause 33, 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


International standards, Technical Barriers to Trade and the WTO Principles

As explained on the ISO/IEC Information Centre, the Agreement on Technical Barriers to Trade (TBT) is one of the legal texts of the WTO Agreement. It obliges WTO Members to ensure that, inter alia, voluntary standards do not create unnecessary obstacles to trade.

In order to improve the quality of International Standards and to ensure the effective application of the TBT, the WTO/TBT Committee has developed 6 principles that clarify and strengthen the concept of international standards under the TBT and contribute to the advancement of its objectives.

These principles concern:

  • transparency
  • openness
  • impartiality and consensus
  • relevance and effectiveness
  • coherence
  • developing country interests

For details of the principles, see Annex 4 to the Second Triennial Review of the TBT Agreement.

These principles are equally relevant to, and should be observed in, the preparation of International Standards (including standards for conformity assessment procedures). The ISO Council has noted that ISO complies well with the WTO principles and has publicized and promoted the principles to all ISO members.