You can also use references when constructing your data model. Using the person data model from Creating Data Models for a Specific Process as an example, you can use reuse the defined reference in several properties of the data model. For example, a reference called ID (which could be an employee ID number), and might be constructed of a user name, and position could be reused in numerous properties. A reference cannot be used in other data models.
To use references in a data model: