IEC 60721-3-9:1993 Classification of environmental conditions - Part 3: Classification of groups of environmental parameters and their severities - Section 9: Microclimates inside products
Defines classes of microclimatic conditions, to which components (basic parts, assemblies, built-in units) may be subjected inside products, and which are used under the climatic conditions classified in IEC 60721-3-3 and IEC 60721-3-4.