Acceptances of simplification of were that each type of entity had only one, simple-evaluated
Acceptances of simplification of were that each type of entity had only one, simple-evaluated attribute of reference because the icons on a chart of road generally correspond to a simple object in the true world. Structured definition of chart - the structured definition of chart follows normal conventions of a ERD, except which it is limited to the types of entity and the types of reports/ratios, for example, there are not any bond of generalization or aggregation.