ABSTRACT
The purpose of classifying knowledge, or the items which house it, has always been closely concerned with saving time. In this century, this factor is most significant. For there certainly are still annual increases in that vast output - so variable in quality and relevance - of local, national or global facts and ideas. And, in terms of the technology available, there is a widening range of choices to help identify or present material. Furthermore, new difficulties are presented by a huge body of 'sub-literature' - much of it potentially ephemeral - emerging in purely electronic form. In the light of these factors any absolutely essential commodity which remains in limited and fixed supply becomes infinitely precious. For many seekers of knowledge or information, that key commodity is undoubtedly 'time'.
