Paterna , F.Campari, I.Scopigno, R.2014-10-212014-10-2119941467-8659https://doi.org/10.1111/1467-8659.1340199In this paper the design of a visual program editor and its specification using formal grammars are discussed. We consider an environment to specify, analyse and execute visual programs for a Geographical Information System (GIS). The lack of sophisticated user interfaces is one of the major drawbacks to Geographical Information Systems, particularly for people without a sound background in computer science. The use of a visual language approach is useful in order to hide the plethora of basic GIS functions, while providing ready- to-use tools to solve users tasks. The visual environment provides users with higher level interfaces- it is based on the module concept, which is conceived as a software building block that implements a solution to a general basic task and is presented to the user through an interactive frame. Complex GIS queries can be carried out by interconnecting modules into flow networks, using a direct manipulation approach.10.1111/1467-8659.1340199199-210