A program suite for the production of articulated subject indexes

A suite of computer programs has been devised to generate articulated subject indexes with machine assistance. The suite has been written for the ICL 1900 series of machines in PLAN assembly language. The application of the index generation algorithm necessitates a double sorting operation. The first of these is straightforward. The strategy of the second is determined by the nature of the algorithm for rearranging index phrases, which is context-sensitive, and therefore requires special procedures for organising the data in core storage. The programs incorporate both tree and letter-table systems for dictionary look-up, and use simple list processing techniques.