ISO/IEC TR 11179-2:2019 compliments ISO/IEC 11179-3 by describing registration of classification schemes and using them to classify registered items in an MDR. Any metadata item can be made a Classifiable_Item so it can be classified, which can include object classes, properties, representations, conceptual domains, value domains, data element concepts and data elements themselves.

This document does not establish a particular classification scheme as pre-eminent. Sanction of a particular taxonomic approach and/or a particular epistemology is also beyond the scope of this document. These are addressed by other standards committees and/or tend to be tailored to a particular domain of discourse. The MDR can establish its own classification schemes, and other standards committees are developing or have developed normative languages for use in classification and/or particular techniques and structures that can be accommodated by this document.

Each registration authority, as described and specified in ISO/IEC 11179-6, can classify classifiable items according to the classification schemes, structures and content that it deems appropriate. In documenting the classification aspects of classifiable items, the registration authority can use the principles, methods, procedures and attributes covered in this document.