Metadata is “data that describes attributes of a resource,” making it possible to find, access, and manage data. For metadata to be useful, one needs repositories of the metadata itself. This paper describes a metadata schema repository that stores the schemas in Extensible Markup Language (XML) document format, rather than the resource description framework (RDF) schema language that has been used elsewhere. A major advantage of this approach is that it allows for the storage of schemas that have a hierarchical structure.

To go into a bit more detail, the metadata can be seen as being structured into three tables: a construction table that contains information on the names and types of the data items; an attribute table that carries the information on which data types are required and whether they are repeatable; and, finally, the DC-correspondence table that relates the schema to the Dublin Core standard. These tables can be encoded into XML in quite a natural way.

It is these XML documents that make up the repository. To make the system usable, the repository system incorporates a Web browser interface to the database of XML schemas that can also be used for the creation of schemas. The user interaction is facilitated by a component that translates between XML and Hypertext Markup Language (HTML). The paper is clearly written and includes sufficient examples to make the content easily accessible.