A crucial requirement for the effective exploitation of geographic information is users' access to the knowledge held in corresponding stored resources, i.e. their understanding of what can be derived from available geographic databases and software. At the core of it is the problem of how to share and reuse knowledge, a major current challenge of Artificial Intelligence (AI). The work presented here extends upon lessons learnt in AI. The proposed solution to the users access issue is an expert system that stores geographical knowledge derivation recipes, and that allows users to browse and customise these recipes. Specifically, we build a model representing the recipes components, i.e. geographic application patterns. This model structures metadata about geographic data and metadata about stored processes, and it describes the usage of these data and processes. A prototype of this system, coded in java, is presented in this paper.