Salman Haider is an award-winning Cataloging & Metadata Librarian, Blogger and Online Social Media Expert. Coming from a Computer Science background, Salman has functional expertise in Resource Description & Access (RDA), AACR2, MARC 21, Library of Congress Classification (LCC), and Library of Congress Subject Headings (LCSH). This blog is about his career highlights, writings in Library and Information Science, and Librarians Personality Development.
We have to encode the subject of a document in order to place the document itself or our records of it in our store. This means that we must in same way be able to specify the subject. Generally an indexer neither has time to read all the documents added to the stock, nor has enough understanding about them. He therefore, uses short cuts-like: the contents page, preface or introduction, or publishers blurb on the book cover; or an abstract if we are looking at a journal article or technical report; or the claims for a patent specification. All of these will give some indication of the subject and will suggest certain lines of thought if we want to pursue the matter further, for example in a dictionary or encyclopaedia.
While indexing we may rely solely on information which is manifest in the document, without attempting to add to this from our own knowledge or other sources. This is derived indexing, that is, indexing derived directly from the document. There are some ways in which derived indexing has been used to produce printed indexes, particularly in computer-based systems. These are now often found in online systems, but the principles remains the same.
However, during the process of indexing, it is practice to distinguish between intellectual and clerical effort involved in an IR system, and computers enable is to carry out the clerical operations at high speed. Derived indexing reduces intellectual effort to a minimum and is thus suited to computer operations, which enables to get a variety of outputs from the one input.