The term cross-reference (abbreviation: xref) can refer to either: * An instance within a

document A document is a writing, written, drawing, drawn, presented, or memorialized representation of thought, often the manifestation of nonfiction, non-fictional, as well as fictional, content. The word originates from the Latin ', which denotes ...

which refers to related information elsewhere in the same document. 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. * In an

index Index (: indexes or indices) may refer to: Arts, entertainment, and media Fictional entities * Index (''A Certain Magical Index''), a character in the light novel series ''A Certain Magical Index'' * The Index, an item on the Halo Array in the ...

, a cross-reference is often denoted by ''See also''. 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''. * In

hypertext Hypertext is E-text, text displayed on a computer display or other electronic devices with references (hyperlinks) to other text that the reader can immediately access. Hypertext documents are interconnected by hyperlinks, which are typic ...

, cross-references take the form of "live" references within the text that, when activated by

mouse click In computing, an event is a detectable occurrence or change in the system's state, such as user input, hardware interrupts, system notifications, or changes in data or conditions, that the system is designed to monitor. Events trigger responses or ...

touch The somatosensory system, or somatic sensory system is a subset of the sensory nervous system. The main functions of the somatosensory system are the perception of external stimuli, the perception of internal stimuli, and the regulation of bo ...

, 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. * 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 In computing, source code, or simply code or source, is a plain text computer program written in a programming language. A programmer writes the human readable source code to control the behavior of a computer. Since a computer, at base, onl ...

. * In a

relational database management system A relational database (RDB) is a database based on the relational model of data, as proposed by E. F. Codd in 1970. A Relational Database Management System (RDBMS) is a type of database management system that stores data in a structured for ...

, a table can have an xref as prefix or suffix to indicate it is a

cross-reference table An associative entity is a term used in relational and entity–relationship theory. A relational database requires the implementation of a base relation (or base table) to resolve many-to-many relationships. A base relation representing th ...

that joins two or more tables together via

primary key In the relational model of databases, a primary key is a designated attribute (column) that can reliably identify and distinguish between each individual record in a table. The database creator can choose an existing unique attribute or combinati ...

Structure

In a document, especially those authored in a

content management system A content management system (CMS) is computer software used to manage the creation and modification of digital content ( content management).''Managing Enterprise Content: A Unified Content Strategy''. Ann Rockley, Pamela Kostur, Steve Manning. New ...

, a cross-reference has two major aspects: * A visible form that appears when the document is presented to the reader * A technical mechanism that resides within the system The visible form contains text, graphics, and other indications that: * Indicate what is being referenced * Enable the reader to follow the cross-reference to the referenced content * May enable the reader to understand what is being referred to, or what to expect upon following the reference * May present to the reader some information from the referenced content The technical mechanism that resides within the system: * Identifies what location is being referred to * Permits the system to present appropriate referencing text when the location containing the reference is presented to a reader * Permits the system to offer a control (such as a link) that a reader can use when the content is presented in electronic form to access the referenced content

Enhancing usability

If the cross-reference mechanism is well designed, the reader will be able to follow each cross-reference to the referenced content whether the content is presented in print or electronically. An author working in a content management system is responsible for identifying subjects of interest that cross documents, and creating appropriate systems of cross-references to support readers who seek to understand those subjects. For an individual cross-reference, an author should ensure that location and content of the target of the cross-reference are clearly identified, and the reader can easily determine how to follow the cross-reference in each medium in which publication is supported. Content strategy practitioners (known as content strategists) specialize in planning content to meet business needs, taking into account the processes for creating and maintaining the content, and the systems that support the content.

References

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