{{distinguish|coreference}} {{Short description|Reference in a book to information at another place in the same work}} {{CS1 config|mode=cs1}}<!--any future usage of {{Citation}} will display with CS1 formatting--> {{Use American English|date=November 2025}} {{Use mdy dates|date=November 2025}}
[[File:Multiple uses of manicule.png|thumb|A cross-reference for ''varuce'' (varice) in Andrew Boorde's ''The Breviarie of Health'' (1502)]]
A '''cross-reference''' (sometimes abbreviated as '''xref''') is an instance within a document which refers the reader to related or synonymous information elsewhere, usually within the same work. To cross-reference is to make such connections.<ref>{{cite book |title=Oxford dictionary of English |date=2010 |publisher=Oxford Univ. Press |location=Oxford |isbn=9780191727665 |edition=3 |entry=cross-reference}}</ref> Cross-references typically link to a related topic. Cross-referencing is usually employed by readers to either verify claims made by an author or to find information on a topic of interest. In both printed and online dictionaries cross-references are important because they form a network structure of relations existing between different parts of data, dictionary-internal as well as dictionary external.<ref>{{citation |first=Sandro |last=Nielsen |date=1999 |title=Mediostructures in Bilingual LSP Dictionaries |work=Lexicographica. International Annual for Lexicography |pages=15, 90–113}}</ref>
Print reference works, such as dictionaries and encyclopedias, have used various typographical elements such as bold text, small caps, or italics; symbols such as the manicule or arrow; and the words ''see also'' or ''for'' to indicate terms that can be cross-referenced. For example, under the term ''Albert Einstein'' in the index of a book about Nobel Laureates, there may be the cross-reference ''See Also: Einstein, Albert''.<ref>{{multiref2 |{{cite book |last1=Trumble |first1=Angus |title=The Finger: A Handbook |date=6 August 2024 |publisher=Macmillan + ORM |isbn=978-1-4299-4561-5 |url=https://www.google.com/books/edition/The_Finger/L__4gEbfi4UC?hl=en&gbpv=1&dq=manicule+index+encyclopedia&pg=PA92&printsec=frontcover |language=en|p=92}} |{{Cite web |last=McHenry |first=Robert |date=December 23, 2015 |title=The Art of the Cross-Reference. |url=https://fortnightlyreview.co.uk/2015/12/art-cross-reference/ |access-date=2025-11-21 |website=The Fortnightly Review |author-link=Robert McHenry |language=en-US}}}}</ref> Cross-references and marginal notes in printed text served a linking function similar to what is seen in hypertext.<ref>{{Cite book |last=Hoff |first=Renske A. |url=https://brill.com/view/title/70135 |title=Involving Readers: Practices of Reading, Use, and Interaction in Early Modern Dutch Bibles (1522–1546) |date=2025 |publisher=BRILL |isbn=978-90-04-69652-5 |doi=10.1163/9789004696525_005|at=ch. 3, sec. 1.2, "Navigating, Hyperlinking, and Generating Knowledge."}}</ref>
[[File:Hyperlinks scheme.svg|thumb|alt=|Diagram of several documents connected by hyperlinks]]
Hypertext cross-references take the form of "live" references within the text that, when activated by mouse click, touch, voice command or other means, immediately makes available the referenced content, which might be a different part of the same document, or another document entirely.<ref>{{cite book |last1=Brewer |first1=Ebenezer Cobham |last2=Rockwood |first2=Camilla |title=Brewer's dictionary of phrase & fable |date=2009 |publisher=Brewer's |location=Edinburgh |isbn=978-0-550-10411-3 |pages=673, 1442 |edition=18th}}</ref>
Related concepts exist within computer science. In programming, "cross-referencing" means the listing of every file name and line number where a given named identifier occurs within the program's source tree.<ref>{{cite web |title=Working with cross-references {{!}} Code Search |url=https://developers.google.com/code-search/user/cross-references |website=Google for Developers |language=en}}</ref><ref>{{cite web |title=Cross Reference Listing |url=https://www.ibm.com/docs/en/i/7.4.0?topic=sbl-cross-reference-listing |website=www.ibm.com |language=en-us |date=June 2012}}</ref> In a relational database management system, a table can have an xref as prefix or suffix to indicate it is a cross-reference table that joins two or more tables together via primary key.<ref>{{cite web |title=Working with Cross References |url=https://docs.oracle.com/cd/E15586_01/integration.1111/e10224/med_xrefs.htm |website=docs.oracle.com}}</ref>
== References == {{reflist}} {{Authority control}} Category:Reference