crossindexed

Crossindexed, or cross-indexing, is a data management and information retrieval practice that connects items across multiple indexes, vocabularies, or metadata schemes to support comprehensive search and interoperable data discovery. It involves creating cross-references, synonym mappings, and concept links that allow a single query to reach items indexed under different terms or classifications.

The primary purpose is to improve recall and precision by bridging term variations, languages, or domain-specific vocabularies. It is widely used in library catalogs, bibliographic databases, digital repositories, and enterprise search systems. Key methods include establishing crosswalks between vocabularies (synonyms, equivalence relationships, broader/narrower terms, related terms), using controlled vocabularies and thesauri, implementing standards such as SKOS, MARC, or Dublin Core, and applying automated mapping techniques.

Implementation typically involves three components: term mapping between indexes, metadata governance to maintain mappings, and user-facing search interfaces that leverage the cross-index links. Ongoing maintenance is essential as vocabularies evolve.

Challenges include handling ambiguity (polysemy), language differences, resource constraints, versioning of vocabularies, and ensuring consistency across systems. Performance considerations include indexing overhead and query expansion effects.

Benefits include improved search effectiveness across diverse collections, better interoperability between systems, and easier discovery for users who may search using different terms.

Examples: in libraries, cross-indexing between author and subject indexes; in health informatics, mapping between MeSH terms and ICD codes; in digital libraries, linking catalog records to full-text repositories.