Gives the characteristics of a categorical structure and the combinatorial rules required for compliance, in order to support the exchange of meaningful surgical procedure information between different national classifications or coding systems of surgical procedures using different national languages within Europe. Applies to: - organisations involved with the development or maintenance of classifications and coding systems for medical procedures namely for multipurpose coding systems on a national or international level. - organisations developing and maintaining software tools allowing natural clinical language expressions analysis, generation and mapping to the main existing classifications of surgical procedures.