In addition, it is a popular and readily available commercial GIS. MCPUIS is “cohesive” [8] in the sense that the decision support methods and visualization methods are encoded into the GIS. The database module is implemented with a RDBMS. This module is used to store and manipulate alphanumeric data. Data in the RDBMS is typically non-spatial in nature (e.g., the cost and flow capacity of a particular type of pipe or valve). The RDBMS used for the development of this work is 4th Dimension (4D) - www.4d.com. It includes a high-level programming language, consisting of several commands and components (data types, variables, operators, expressions, commands and methods) that help to perform tasks and manage the data, allowing a full integration of data manipulation with models through gr aphical interfaces. MCPUIS is provided with an interface designed to be user-friendly and intuitive for the user, allowing the easy introduction of all the parameters required by the methods and the experimentation with the decision support methods implemented (e.g., to facilitate sensitivity analysis with different sets of parameters and with the results provided by distinct methods).