International Standards and Conformity Assessment for all electrical, electronic and related technologies
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Organization and subdivision
of subject matter


Names of the main subdivisions

The terms which shall be used to designate the divisions and subdivisions of subject matter are given in Table 1 in English and in French.


Table 1 – Names of divisions and subdivisions

English term

French term

Example of numbering






[no number]





Subdivision into documents

Documents are so diverse that no universally acceptable rules can be established for the subdivision of the subject matter.


However, as a general principle, an individual document shall be prepared for each subject to be standardized, and published either as a single standard or a single part of a series.


EXAMPLE 1 Examples of reasons for the subdivision into parts under the same number are
–    the document is likely to become too long,
–    subsequent parts of the content are interlinked,
–    portions of the document could be referred to in regulations, and
–    portions of the document are intended to serve for certification purposes.


Such subdivision has the advantage that each part can be revised separately as necessary.


In particular, the aspects of a product which will be of separate interest to different parties (e.g. manufacturers, certification bodies, legislative bodies or other users) shall be clearly distinguished, preferably as parts of a document or as individual documents.


EXAMPLE 2 Examples of such individual aspects are
–    health and safety requirements,
–    performance requirements,
–    maintenance and service requirements,
–    installation rules, and
–    quality assessment.


Subdivision of the subject matter within a series of parts

There are two main ways of subdividing subject matter within a series of parts.


a) Each part deals with a specific aspect of the subject and can stand alone.


Part 1: Vocabulary
Part 2: Requirements
Part 3: Test methods
Part 4: …


Part 1: Vocabulary
Part 2: Harmonics
Part 3: Electrostatic discharge
Part 4: …


b) There are both common and specific aspects to the subject. The common aspects shall be given in Part 1. Specific aspects (which can modify or supplement the common aspects and therefore cannot stand alone) shall be given in separate individual parts.


Part 1: General requirements
Part 2: Thermal requirements
Part 3: Air purity requirements
Part 4: Acoustical requirements


Part 1: General requirements
Part 21: Particular requirements for electric irons
Part 22: Particular requirements for spin extractors
Part 23: Particular requirements for dishwashers


EXAMPLE 5 For IEC documents only
Part 1: General requirements
Part 2-1: Requirements for plasma displays
Part 2-2: Requirements for monitors
Part 2-3: Requirements for LCDs


Where the system described in b) is used, care shall be taken that the references from one part to another are valid. There are two ways of achieving this.

  • If reference is made to a particular element, the reference shall be dated (see dated references).
  • When undated references (see undated references) are used, the committee responsible shall validate the references at the time of review of the document.

Each part of a multipart document shall be drafted in accordance with the same rules as those used for an individual document.


The number of a part shall be in Arabic numerals, starting with 1, following the document number and preceded by a hyphen.


EXAMPLE 6 ISO 9999-1, ISO 9999-2


In ISO, parts cannot be further subdivided. In IEC, parts can be subdivided down to two levels. See the examples in Title - numbering and subdivision.


EXAMPLE 7 IEC 60335-2-9


If a document is subdivided in a number of separate parts, the first part should include an explanation of the intended structure in its introduction. When developing a series, consider reserving Part 1 for general aspects such as a vocabulary.


In the foreword of each part in the series, a reference may be made to the titles of all other parts that have been or are planned to be published.




A list of all the parts in the ISO xxxx series, published under the general title xxx, can be found on the ISO website.


A list of all the parts in the IEC xxxx series, published under the general title xxx, can be found on the IEC website.


Subdivision of the subject matter within an individual document

An example of a typical arrangement is given in Table 2.


Table 2 – Overview of the major subdivisions of a document
and their arrangement in the text

Major subdivision










Normative references


Terms and definitions


Symbols and abbreviated terms


Technical content
For example: test methods






a   See Introduction - mandatory, conditional, optional.

b   When no normative references or terms are listed, use the introductory texts provided in the boilerplate text document..