An Integrated Computer-Aided Software Engineering Environment (ICASE) is a software system that can support the development, maintenance, and use of enterprise-wide information resources. An ICASE requires a data model that can represent heterogeneous types of entities and relationships evolving in time and context. This paper describes a data model called FORM (Flexible Object-Relationship Model) for the object management system of ICASEs. FORM is an extended object-oriented data model adopting concepts in semantic data modeling and meta-modeling. Relationship types as well as entity types, both of which can be defined as objects in an object schema help integrate heterogeneous concepts; and meta-types that hold adaptable semantics of object manipulation help raise the automation level of ICASEs. An object-modeling approach for version control is illustrated to show the effectiveness of the framework.