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Assigned Indexing

Assigned Indexing

Assigned Indexing (or Assignment Indexing or Concept Indexing) in an indexing method in which the human indexer selects one or more subject headings or descriptors from a list of controlled vocabulary (e.g. subject headings lists, thesaurus, or classification schemes) to represent the subject matter of the work. Since the Assigned Indexing uses the controlled vocabulary to give the indexing terms selected to represent the subject content of a work, so in this technique there is no need for the index terms to appear in the title or text of the document indexed.

In indexing, if the terms are selected from the title or the text of a document and used without any alteration as index terms, then this is referred to as natural language indexing or derived indexing. Derived Indexing solely relies on information which is manifest in the document, without attempting to add to this from indexer’s own knowledge or other sources. By doing so we have to face the problems of natural language. If however, the selected terms are translated or encoded into authorized terms by the help of a prescribed list (e.g., Library of Congress Subject Headings, Library of Congress Classification, Dewey Decimal Classification), then the indexing language becomes controlled or artificial. This process is called Assigned Indexing.

If we are to use a list of words to help us in our searching, we would increase the chances of achieving successful matches if we used the same list of words to encode the appropriate words to the documents ourselves rather than rely on authors’ choice. In other words, we devise an indexing language and use this for both encoding operations: input and question. Such systems are referred to as assigned indexing systems. Assigned indexing involves an intellectual process. Subject heading schemes, thesaurus and classification schemes are the popular forms of assigned indexing.

Assigned indexing is also known as concept indexing because what we are trying to do is to identify the concepts involved in each document.


  • Examples of Assigned Indexing
  • Advantages of Assigned Indexing
  • Assigned Indexing: Relationships

Examples of Assigned Indexing

Subject heading schemes (e.g. LCC, DDC, LCSH, SLSH), thesaurus (e.g. Roget's Thesaurus), and classification schemes (e.g. DDC, LCC, UDC) are the popular forms of assigned indexing.

Check the example of the following bibliographic record which is given from our article Cataloging Metadata Examples : RDA AACR2 LCSH LCC DDC MARC-21 BIBFRAME Etc.  In this catalog record, the subject of this book is given in the form of LCSH headings, DDC number, and LCC number. This subject representation is an example of Assigned Indexing as the subject headings are given from the controlled vocabulary LCSH and class numbers are given from the classification schemes DDC and LCC.

000Leader01499cam a22003975i 4500
001Control Number21035302
005Date and Time of Latest Transaction20190626080219.0
008Fixed-Length Data Elements190626t20162016nyua 000 0 eng d
010Library of Congress Control Number|a 2019295036
016National Bibliographic Agency Control Number7_|a 017845848 |2 Uk
020International Standard Book Number|a 1574403834
020International Standard Book Number|a 9781574403831
035System Control Number|a (OCoLC)ocn949911758
040Cataloging Source|a YDXCP |b eng |c YDXCP |e rda |d IQU |d BTCTA |d OCLCF |d HLS |d OCLCQ |d HUL |d UKMGB |d DLC
042Authentication Code|a lccopycat
050Library of Congress Call Number00|a Z694.15.R47 |b H35 2016
082Dewey Decimal Classification Number04|a 025.32 |2 23
100Main Entry--Personal Name1_|a Haider, Salman, |e author.
245Title Statement10|a Survey of emerging cataloging practices : |b use of RDA by academic libraries / |c by Salman Haider and Primary Research Group Staff.
264Production, Publication, Distribution, Manufacture, and Copyright Notice_1|a New York : |b Primary Research Group, |c [2016]
264Production, Publication, Distribution, Manufacture, and Copyright Notice_4|c ©2016
300Physical Description__|a 111 pages : |b illustrations ; |c 28 cm
336Content Type__|a text |b txt |2 rdacontent
337Media Type__|a unmediated |b n |2 rdamedia
338Carrier Type__|a volume |b nc |2 rdacarrier
630Subject Added Entry-Uniform Title00|a Resource description & access.
650Subject Added Entry - Topical Term_0|a Academic libraries.
650Subject Added Entry - Topical Term_0|a Descriptive cataloging |v Rules.
630Subject Added Entry-Uniform Title07|a Resource description & access. |2 fast |0 (OCoLC)fst01791077
650Subject Added Entry - Topical Term_7|a Academic libraries. |2 fast |0 (OCoLC)fst00794997
650Subject Added Entry - Topical Term_7|a Descriptive cataloging. |2 fast |0 (OCoLC)fst00891123
655Index Term-Genre/Form_7|a Rules. |2 fast |0 (OCoLC)fst01423857
710Added Entry-Corporate Name2_|a Primary Research Group, |e author, |e issuing body.

Advantages of Assigned Indexing

Advantages of Assigned Indexing are overcoming the Problems of Natural Language in Indexing which are briefly given below. 
  • Problems inherent in the language
    • Synonyms: as the preferred term is indexed and synonyms or related terms direct the user to the preferred term
    • Homographs: removes any confusion caused by homographs by the inclusion of a qualifying term
    • Use of Plural-Singular Forms
    • Multi-Worded Concept
    • Complex Subject
  • Problems Pertaining to Relationships
    • Semantic Relationships
    • Syntax

Assigned Indexing: Relationships
  • Assignment Indexing
  • Concept Indexing 
Broader Term
  • Indexing
Related Term
  • Automatic Indexing
  • Derived Indexing

  1. Information Access Through The Subject : An Annotated Bibliography / by Salman Haider. - Online : OpenThesis, 2015. (408 pages ; 23 cm.) 

  • Last Updated 2019-08-10
  • Written 2017-02-24

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