The terms 'normative' and 'informative' are commonly used in IEC and other derivative standards to define applications of annexes. A normative annex is an integral part of a Standard which requires mandatory compliance, whereas an informative annex is for information and guidance only, compliance of which is optional.
In the context of the International Electrotechnical Commission (IEC), normative and informative annexes serve different purposes
Normative Annexes: These are annexes that contain requirements, recommendations, or guidelines that are considered essential for understanding and applying the standard. Normative annexes provide additional technical specifications, testing methods, or other normative content that is integral to the standard itself. Compliance with the content of normative annexes is typically necessary for meeting the requirements of the standard.
Informative Annexes: Informative annexes, on the other hand, provide supplementary information that may aid in the understanding or implementation of the standard but are not considered mandatory for compliance. They often include explanatory notes, examples, additional background information, or guidance on best practices. Informative annexes are intended to provide helpful context or additional insights into the subject matter covered by the standard but do not contain requirements that must be met for compliance.
Example of Compliance
A good example of this was when a third party review queried the design of a gas anaylyzer shelter. The query states that the analyzer shelter is not adequately ventilated creating a Zone 1 as per AS/NZS 60079.10.1-2009 Table ZA.1 - Ventilation Criteria Item 2.a to quote
(a) Within a structure having no more than three walls and where all walls have continuous or virtually continuous ventilation openings along their full length comprising not less than 0.4 m high effective opening at the bottom, 0.3 m high effective opening at the top of the walls and 0.3 m virtually continuous effective opening at the highest part of the roof
The designer's explanation was that Annex ZA was informative rather than normative. A more detailed analysis was performed for the shelter and have indicated that the gas release was very small creating only a low and easily diluted gas up to a negligible extend by ambient air movement. Given this scenario, it was confirmed that the shelter ventilation will be assessed as medium degree with good availability. This analysis will make the gas analyser shelter to be classified only as Zone 2.
What the Designers Need to Do?
Normative annexes contain essential requirements or specifications that must be adhered to for compliance with the standard, while informative annexes offer supplementary information that can enhance understanding or provide additional guidance but are not mandatory for compliance.