A description of the structure given to a set of metadata elements.
A metadata scheme or schema defines the relationships between individual metadata elements.
The term "schema" is often applied to any document describing these relationships. Traditionally, though, the word "schema" refers to a diagrammatic representation, while "scheme" would be used to refer to a textual description.
The IMS Learning Resource Meta-Data specification is both a scheme and a schema, because it uses diagrams and text to define the relationship between elements and sub-elements. The specification of contolled vocabularies and encoding schemes can be used for each element also comprises part of the scheme/schema, since the scope of each element is limited by these features, and thus it's relationship with other elements is defined by its scope.
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