Used to describe the levels of the code list hierarchy. The level describes the nesting structure of a hierarchical coding structure. A level could have data attached to it (summary of its children) or no data attached to it (the equivalent of creating a category group in 2.0 and earlier versions Note that the attribute levelNumber is used for referencing specific codes to their level identifier. Although Code Lists can be physically nested, the use of a Level description and the level number on a specific code is needed to specify subsets of the CodeList for use in CodeRepresentations by level specification. Provides a name, description and level number. Specifies the relationship between the categories at that level and interval value if the relationship has the value of Interval.