Chemical Abstracts material on‐line

Chemical Abstracts Issues and Indexes have been available in printed form since 1907. Microform versions are also available now. In the near future Chemical Abstracts material will be accessible by computer in the UK via six on‐line systems and one batch current awareness system. This variety of modes of access is further diversified by the variety of ways in which the original Chemical Abstracts Service (CAS) files have been implemented for use with the different search systems, and by the differences in the system facilities, pricing structure and technical back‐up offered by the service suppliers. This paper attempts to bring together in tabular form factors which should be considered in taking rational decisions on how to get the ‘best’ out of Chemical Abstracts material, the ‘best’ being the optimum performance/cost ratio for any given topic.