Editing Document classification (section)

=="Content-based" versus "request-based" classification==
'''Content-based classification''' is classification in which the weight given to particular subjects in a document determines the class to which the document is assigned. It is, for example, a common rule for classification in libraries, that at least 20% of the content of a book should be about the class to which the book is assigned.<ref>Library of Congress (2008). The subject headings manual. Washington, DC.: Library of Congress, Policy and Standards Division. (Sheet H 180: "Assign headings only for topics that comprise at least 20% of the work.")</ref> In automatic classification it could be the number of times given words appears in a document.

'''Request-oriented classification''' (or -indexing) is classification in which the anticipated request from users is influencing how documents are being classified. The classifier asks themself: “Under which descriptors should this entity be found?” and “think of all the possible queries and decide for which ones the entity at hand is relevant” (Soergel, 1985, p.&nbsp;230<ref>Soergel, Dagobert (1985). [https://books.google.com/books?id=cHbNCgAAQBAJ Organizing information: Principles of data base and retrieval systems]. Orlando, FL: Academic Press.</ref>).

Request-oriented classification may be classification that is targeted towards a particular audience or user group. For example, a library or a database for feminist studies may classify/index documents differently when compared to a historical library.  It is probably better, however, to understand request-oriented classification as ''policy-based classification'': The classification is done according to some ideals and reflects the purpose of the library or database doing the classification. In this way it is not necessarily a kind of classification or indexing based on user studies. Only if empirical data about use or users are applied should request-oriented classification be regarded as a user-based approach.