CRANV1P1 Indexing Procedures chapter Cyril Cleverdon Jack Mills Michael Keen Cranfield An investigation supported by a grant to Aslib by the National Science Foundation. Use, reproduction, or publication, in whole or in part, is permitted for any purpose of the United States Government. - 52 - not depend on the context of the individual report being indexed but on the context of the index language as a whole; in other words, the relations were paradigmatic rather than syntagmatic. It may be noted that all the devices measurable by Method (2) are recall devices - i. e. , devices for elaborating or expanding the classes given in the index description of a document. (3) To incorporate particular devices in the original indexing but in such a way as to mal;e [OCRerr].hem detachable when required; e.g. , to attach weights to terms which could be cG[OCRerr]mted when figures for weighted indexing were required but ignored for unweighted u[OCRerr]dexing. This method, also much less laborious than Method (1), would be particularly appropriate for those precision devices which depended on the context of the individual report being indexed, and which could not therefore be measured by Method (2). It was finally decided that the indexing proper should be done on the basis of Method (3); that is to say, the indexing would be basically post coordinate, and take into account only the precision devices of weighting, links and roles (whilst observing a high degree of exhaustivity and specificity). Method (2) was to be used in the measurement of the recall devices of Synonyms, Word-forms and Hierarchical linkage (generic and non-generic). Associative indexing could not be measured within the conditions above, but it was hoped that the indexing would be sufficiently exhaustive to allow some tests of associative techniques to be made by other investigators. Te Nuyl's device was also ignored at this point, since it was clear that our indexing language could always be translated into dictionary-based clusters when necessary for measurement by Method (2). Bibliographical coupling, since its classes are not defined by subject description[OCRerr] required quite separate measurement and is discussed in Chapter 7. The major precision device of coordination is, in a post coordinate system, purely a search device and its measurement does not .fit exactly into either Method (2) or (3). It is perhaps necessary to mention at this point that post coordination in itself does not constitute an indexing device. It is essentially a method of recording subject descriptions in a physical form which allows equally free access to whatever combina- tions of terms are requested. A precoordinate system, on the other hand, allows direct access only to certain selected combinations of terms. Other combinations constitute distributed relatives and access to them is to this extent made less con- venient (although it is by no means forbidden, or made impossible, as is sometimes suggested). But the class defined by coordinating two or more terms is exactly the same, whether the operation is performed at the indexing stage (precoordination) or at the search stage ( post coordination). The relative convenience with which access to such a class is gained was not something with which this investigation was con- cerned. The form in which the indexing was recorded is best shown by Fig. 4.1 which shows the index sheet for ˘locament 1590. Author and title details were printed on the sheet. The indexer then analysed the document in four stages, firstly, 'concepts, were distinguished as a " first-stage mterfixing device ('link,); these are not easily defined (and this must be recognized as a theoretical weakness) but their practical function was reasonably clear. This was to remove the first level of vagueness and ambiguity inherent in words taken singly, by not accepting adjectival forms alone but only in conjunction with the terms they qualified. So terms which in isolation are weak and virtually useless as retrieval handles were given the necessary context; such terms as High, Number, Coefficient, Main, Trailing, Angle, Aspect which in practice do not form classes for which requests are made, appeared in conjunction