Abstract
Feature-based modeling is being given an increasing significance in the development of computer-aided design environments, due to its expressive power in capturing various aspects of designer intent. Integrity problems arise, however, when the specification of complex shapes requires several features to overlap or interact. In this paper we address the problem of form feature behavior representation for such situations, developing a semantic model that captures the actual contribution of each feature in the overall model shape. Within this semantic framework it becomes possible to establish naturally and flexibly the desired validity conditions for each feature class, enhancing a modeling system with the ability for permanently monitoring each feature's conformity with that original specification.