A data model, called the entity-relationship model, is proposed. This model incorporates some of the important semantic information about the real world. A special diagrammatic technique is introduced as a tool for database design. An example of database design and description using the model and the diagrammatic technique is given. Some implications for data integrity, infor-mation retrieval, and data manipulation are discussed. The entity-relationship model can be used as a basis for unification of different views of data: t,he network model, the relational model, and the entity set model. Semantic ambiguities in these models are analyzed. Possible ways to derive their views of data from the entity-relationship model are presented. Key Words and Phrases: database design, logical view of data, semantics of data, data models, entity-relationship model, relational model, Data Base Task Group, network model, entity set

Successful communication of ideas has been and will continue to be a limiting factor in man's endeavors to survive and to better his life. The invention of algebra, essentially a graphic technique for communicating truths with respect to classes of arithmetic statements, broke the bond that slowed the development of mathematics. Whereas "12+ 13=25 ' ' and "3+7 = 10 " and "14+(-2) = 12" are arithmetic statements, "a+b=c ' ' is an algebraic statement. In particular, it is an algebraic statement controlling an entire class of arithmetic statements such as those listed. Data Structure Diagrams The Data Structure Diagram is also a graphic technique. It is based on a type of notation dealing with classes--specifically, with classes of entities and the classes of sets that relate them. For example, individual people and automobiles