Abstract
Requirements analysis and design specification is a serious issue in software engineering because of semantics involved in the transformation of real world problems to computational models. Unified Modeling Language (UML) has been accepted as a standard for design and development of object oriented systems. Unfortunately, most of UML structures are based on graphical notations and are prone to causing errors. That means UML has a lack of notations for description of a complete functional system and its semantics is still semi-formal allowing ambiguities at design level. Formal methods have played a vital role, particularly, at requirement analysis and design level but, for a moment, are not fully welcomed because of involving much mathematics. Therefore, a concrete linkage of UML and formal methods is needed to overcome the above issues. In this paper, an integration of UML and Z notation is defined for class diagrams considering both the syntax and semantics at an abstract level of specification. Four major kinds of relationships, i.e., association, generalization, aggregation and composition are addressed. The formal specification is analyzed and validated using Z/Eves tool.