ISR10 The Indexing Function chapter Joseph John Rocchio Harvard University Gerard Salton Use, reproduction, or publication, in whole or in part, is permitted for any purpose of the United States Government. 2-2 2. Manual Indexing The increasing emphasis which has been placed in recent years * on coping with the rising flow of technolo[OCRerr]cal literature has stimulated * study of the traditional [OCRerr]oals and procedures of the various activities 1* 0£ documentation and library facilities. The range of services offered by such facilities is too broad to be considered here. Since subject classification and document indexing play a primay role in facilitating the accessibility of recorded knowled[OCRerr]e, these facets of documentation have been examined with particular care.2'3'4'5 Such activities are directly concerned with the document retrieval problem, and thus are [OCRerr]rmane to this discussion; on the othe'r hand, the present obj[OCRerr]ective is to consider mechanized systems for liter[OCRerr]ture searching. The theory' and methodolDgy of manual indexing must, therefore, largely be i[OCRerr]ored. In so far as manual indexing is considered as an input process for mechanized search and retrieval systems, its goals are similar to those of automatic indexing. In this sense, the limitations of current techniques for linguistic data processing normally dictate the form and structure of the index langunge. Thus the scope of both manual and automatic index transformations for mechanized retrieval are largely the' same and the distinction between' the two is not critical for an examination of' the structure 0£ index representations of information content[OCRerr] suitable for mechanized [OCRerr]rocessing. 3. Automatic indexing The goal of automatic indexing is to develop a set of computer-