A reference is a special definition that provides access to variables, attributes, and other properties that belong to another entity, collection, or sub-collection.  References are very important because the connect all the components of the sytem being modeled.

References use attribute values or literal strings to connect to other entities by matching the key values.  References can be used in equations or other expressions to get a specific value for a specific variable or attribute.  The format in the Ventity language is "Reference Name" +  "."  + "Variable Name".