Crosswalk (metadata)

A crosswalk is a table that shows equivalent elements (or "fields") in more than one database. It maps the elements in one metadata scheme to the equivalent elements in another scheme. Example:

This is why crosswalks are said to be "lateral" (one-way) mappings from one scheme to another. Separate crosswalks would be required to map from scheme A to scheme B and from scheme B to scheme A. ["Metadata Fundamentals for All Librarians," Priscilla Caplan, American Library Association, Chicago, 2003, p.39]

Some other mapping problems are:

*One scheme may have one element that needs to be split up with different parts of it placed in multiple other elements in the second scheme ("one-to-many" mapping)

*One scheme may allow an element to be repeated more than once while another only allows that element to appear once with multiple terms in it

*Schemes may have different data formats (eg: "John Doe" or "Doe, John")

*An element in one scheme may be indexed but the equivalent element in the other scheme is not
*Schemes may use different controlled vocabularies

*Schemes may change their standards over time

Some of these problems are simply not fixable. As Karen Coyle says in "Crosswalking Citation Metadata: The University of California's Experience,"

"The more metadata experience we have, the more it becomes clear that metadata perfection is not attainable, and anyone who attempts it will be sorely disappointed. When metadata is crosswalked between two or more unrelated sources, there will be data elements that cannot be reconciled in an ideal manner. The key to a successful metadata crosswalk is intelligent flexibility. It is essential to focus on the important goals and be willing to compromise in order to reach a practical conclusion to projects." [in "Metadata in Practice" Diane I. Hillmann and Elaine L. Westbrooks, eds., American Library Association, Chicago, 2004, p. 91.]

Examples

MARC to Dublin Core (Library of Congress) http://loc.gov/marc/marc2dc.html

USMARC to EAD (Getty)http://www.getty.edu/research/conducting_research/standards/intrometadata/usmarc_ead.html

Dublin Core to MARC21 (Library of Congress) http://www.loc.gov/marc/dccross.html

Dublin Core to UNIMARC (UKOLN)http://www.ukoln.ac.uk/metadata/interoperability/dc_unimarc.html

Dublin Core to EAD (Getty) http://www.getty.edu/research/conducting_research/standards/intrometadata/dc_ead.html

TEI header to USMARChttp://etext.lib.virginia.edu/tei/tei-marc.html/

FGDC to USMARC (Alexandria) http://www.alexandria.ucsb.edu/public-documents/metadata/fgdc2marc.html

EAD to ISAD(G) (Getty)http://www.getty.edu/research/conducting_research/standards/intrometadata/ead_isad.html

ISAD(G) to EAD (Getty) http://www.getty.edu/research/conducting_research/standards/intrometadata/isad_ead.html

ONIX to MARC21 (LC) http://www.loc.gov/marc/onix2marc.html

VRA to MARC (Indiana University) http://php.indiana.edu/%7Efryp/marcmap.html

Metadata Mappings (MIT Library)http://libraries.mit.edu/guides/subjects/metadata/mappings.html

Mapping Between Metadata formats (UKOLN) http://www.ukoln.ac.uk/metadata/interoperability/

International Metadata Standard Mappings (Academia Sinica) http://www.sinica.edu.tw/%7Emetadata/standard/mapping-foreign_eng.htm

References

Reflist

See also

* Meta tag
* Metadata
* Database

External Links

[http://www.oclc.org/research/researchworks/schematrans/default.htm "Metadata Crosswalk Depository" (SchemaTrans)] (OCLC)

[http://www.ukoln.ac.uk/metadata/interoperability "Mapping Between Metadata Formats"] (UKOLN)

[http://www.getty.edu/research/conducting_research/standards/intrometadata/path.html "Crosswalks the Path to Universal Access?"] (Getty)

[http://www.dlib.org/dlib/june06/chan/06chan.html "Metadata Interoperability and Standardization - A Study of Methodology Part I"] (D-Lib)