This Chen ERD Visio shows how different entities (such as customers and products) in a database relate to one another. Visio includes stencils for three different types of entity relationship diagrams. Each employs distinct symbols to represent entities and their interrelationships. Visio also allows you to reverse-engineer a database model from an existing one. Visio also includes a stencil for creating a data-flow diagram, which shows the outputs and inputs of each entity and the process itself. Entities, attributes, relationships, and cardinality are the primary components of Chen ERD notation. While a traditional ER diagram depicts attributes as part of entities, Chen ERDs depict them as individual boxes, just one example of the additional detail and depth provided by Chen ERDs.