Crosswalks

Interoperability, particularly semantic interoperability, can also be facilitated through the use of crosswalks, which are authoritative mappings of metadata elements from one schema to another (Caplan, 2003). By analyzing the metadata elements in separate schemas and correlating the similar fields, metadata creators can “map” the equivalent relationships between the schemas. Thus, crosswalks are the “maps” that show these relationships (Woodley, 2000). Crosswalks are most useful when the schemas are relatively simple, are for similar communities or types of materials, and have overlapping concepts. Mapping becomes much more difficult when it involves cross-domains, schemas of different complexities, and schemas with great semantic differences (Taylor, 2004).

Crosswalks are primarily used as a basis for specifications of the physical conversions of records from one metadata schema to another with regards to record exchange. However, since crosswalks only provide lateral or one-way mapping from one schema to another, separate crosswalks are required to map from schema A to schema B and then from schema B to schema A. As a result, some information can become distorted or lost among pairs of crosswalks. This means that the information retrieved after a reversion may not be identical to the original (Taylor, 2004).

The Library of Congress provides a good example of the MARC to Dublin Core Crosswalk, which is available at http://www.loc.gov/marc/marc2dc.html.


References:

Caplan, P. (2003). Metadata fundamentals for all libraries. Chicago: American Library Association.
Taylor, A.G. (2004). The organization of information (2nd ed.). Westport, CN: Libraries Unlimited.
Woodley, M.S. (2000). Crosswalks: The path to universal access? In Introduction to metadata: Pathways to digital information. Retrieved July 1, 2008 from http://www.getty.edu/