Details of formalized relations in feature models using OCL

System families are a form of high level reuse of development assets in a specific problem domain, by making use of commonalities and variabilities. To represent assets belonging to the core of the family and assets belonging to variable parts, feature modeling is a widely used concept. Consistency checking in feature models is not yet addressed appropriately by current methods. This paper gives a brief overview of feature modeling and elaborates the problems of current approaches. Based on the applications of these approaches within an ongoing research project this paper proposes a formalized definition for feature modeling using the Object Constraint Language (OCL) and a set of associations and constraints to be used in the feature model. The relations between features in the feature model and features to external assets are examined and a way to formally handle these relations is presented as a result of a research project.