The ARC/INFO GIS stores a network as a combination of line features (links) and point features
(nodes) with associated attributes. The features consist of their geographical coordinates and the key totheir attributes which are stored in tables managed by a relational database management system
(RDBMS). Detailed results of network analyses are stored in a GIS as additional attributes of the network
database. External models and data can also be linked to the GIS using a macro language, thus making the
execution of external programs ‘transparent’ to the user.