What are the meanings and uses of "normative,  informative, Shall, Should, May, Can"?

Issue:

What is the meaning of "normative" and "informative", and to what does each apply? In cases where the terms "normative" and "informative" are used, they seem to be used in a manner inconsistent with the dictionary definitions, yet there is no definition within the CC or CEM. In other cases (such as paragraph 23 of CEM Part 2, Section 1.3.2), there is no clear statement of whether guidance text accompanying work units and sub-tasks is normative or informative.

In addition, the phrase "Application Notes" is used in the context of both the CC/CEM and PPs. Are both contexts comparable?



Interpretation

The following terms are used in accordance with the ISO definitions contained in ISO/IEC Directives Part 2, Rules for the structure and drafting of International Standards: "Normative", "informative", "Shall", "Should", "May", and "Can". The ISO definition for each is to be added to the glossary in CC, Part 1.

All portions of the CC and CEM should be considered "Normative" unless specifically denoted as "Informative".

Any inconsistencies with this usage will be addressed in a future version of the CC.

Specific Changes

The following changes are made to the CEM Part 2 v1.0:

    Paragraph 23 of CEM Part 2, Section 1.3.2, is changed as follows:

    Guidance text accompanying work units and sub-tasks gives further explanation on how to apply the CC words in an evaluation. The described method is normative, meaning that the verb usage is in accordance with ISO definitions for these verbs; that is: the auxiliary verb "should" is used when the described method is strongly preferred and the auxiliary verb "may" is used where the described method(s) is allowed but no preference is indicated. (The auxiliary verb "shall" is used only for the text of work units.)

The following changes are made to the CC v2.1 Part 2:

        The text of paragraphs 9 and 10 are replaced with:

        Annex A provides explanatory information for potential users of the functional components including a complete cross reference table of the functional component dependencies. Annexes B through M provide explanatory information for the functional classes. They are a repository for supporting material for the users of this part of the CC, which may help them to apply relevant operations and select appropriate audit or documentation information.

        The identifier for each of the Annexes is changed from "informative" to "Normative".

        The text of paragraph 526 is replaced with:

        This annex contains additional guidance for the families and components defined in the elements of this CC Part 2, which may be required by users, developers or evaluators to use the components. To facilitate finding the appropriate information, the presentation of the classes, families and components in this annex is similar to the presentation within the elements.

        The text of paragraph 543 is replaced with:

        The following annexes C through M provide explanatory notes for the functional classes defined in the main body of this part of the CC.

The following additions are made to the CC v2.1 Part 1, Subclause 2.3 Glossary:

    Normative: Normative text is that which "describes the scope of the document, and which set out provisions." (ISO/IEC Directives, Part 2) Within normative text, the verbs "shall", "should", "may", and "can" have the ISO standard meanings described in this glossary and the verb "must" is not used. Unless explicitly labeled "informative", all CC text is normative. Any text related to meeting requirements is considered normative.

    Informative: Informative text is that which "provides additional information intended to assist the understanding or use of the document."(ISO/IEC Directives, Part 2). Informative text is not related to meeting requirements.

    Shall: Within normative text, "shall" indicates "requirements strictly to be followed in order to conform to the document and from which no deviation is permitted." (ISO/IEC Directives, Part 2)

    Should: Within normative text, should indicates "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."(ISO/IEC Directives, Part 2) The CC interprets 'not necessarily required' to mean that the choice of another possibility requires a justification of why the preferred option was not chosen.

    May: Within normative text, may indicates "a course of action permissible within the limits of the document"(ISO/IEC Directives, Part 2)

    Can: Within normative text, can indicates "statements of possibility and capability, whether material, physical or causal"(ISO/IEC Directives, Part 2)

Rationale:

It was the original intention of the CEM authors to make the guidance text normative. In order to avoid confusion between the guidance text and the work units or sub-tasks, it was decided by the CEM authors not to use the verb "shall"; however, this original intention is not clearly stated in the referenced paragraph. It was never the intention of the CEM authors to make any part of the CEM informative verses normative. Because the relationship of the annexes to Part 2 is the same as the relationship of the CEM to Part 3, the Part 2 annexes are likewise normative. They were inadvertently mislabelled as "informative" when v2.1 was published.

The interpretation simply makes explicit the ISO standard definitions that have always been used within the CC and restores the intended labeling of the Part 2 annexes.

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