Towards a General Theory of Scope

One key requirement of topic maps from the earliest days was to be able to merge indexes from disparate origins. This requirement accounts for two further concepts that greatly enhance the power of topic maps: subject identity and scope. This paper concentrates on scope, but also includes a brief discussion of the feature known as the topic naming constraint, with which it is closely related. It is based on the authors' experience in creating topic maps and in implementing processing systems for topic maps (in particular, the Ontopia Topic Map Engine and Navigator.