1. BACKGROUND TO THE PROBLEM OF INCREMENTAL UPDATING AND

As well as a number of Commissions, the International Cartographic Association (ICA) had one Working Group, on Incremental Updating and Versioning, and this presentation describes some of the work undertaken recently by the Working Group (WG). The WG was voted for a Commission by the General Assembly held at the 21st ICC in Durban, South Africa. The basic problem being addressed by the Commission is that a user compiles their data base using core data sets from various sources, integrating them together for their particular needs and building their own, value-added data and topology on top. The user’s primary concern is their value-added data, maintaining their integrity, quality and spatial referencing; however, the core data sets provide the crucial spatial framework for the value-added data. Unfortunately, geographical data are dynamic and most suppliers maintain and update their core data sets. Such updates could be: continuous (eg: telemetry), periodic (eg: daily, monthly or annually), part of a planned update cycle (eg: for a national mapping series), when the amount of change or number of errors crosses a threshold, or by special request (eg: to prepare for a census or election). Historically, updates have been provided in bulk, with the new data set replacing the old one. User could: ignore update (if it is not significant enough), manually (and selectively) update their dat