Classification of environmental conditions - Part 3: Classification of groups of environmental parameters and their severities - Section 9: Microclimates inside products
This section of IEC 721-3 defines classes of microclimatic conditions, to which components (basic parts, assemblies, built-in units) may be subjected inside products, which are used under the climatic conditions as classified in sections IEC 721-3-3 and IEC 721-3-4.