08afeb41_Model___UNECE_Statistics_Wikis__Object
[Group] Concepts [Definition] A set of related Classification Schemes. The Classification relates Classification Schemes which differ as versions or variants of each other. [Explanatory Text] For example, NAICS (North American Industrial Classification System) is a Classification, but NAICS 2002 and NAICS 2007 are Classification Schemes, as they are different versions of NAICS. [Object] 
Classification
Annex C Glossary - Generic Statistical Information Model - UNECE Statistics Wikis