After you've added fields to definitions that represent data entities in your system, you may want to add constraints on them that govern what they can store and how they are displayed. For example, an AppointmentTme field for an Appointment definition might be restricted to a range of hours. Other types of constraints include a specification of valid values, whether or not the field is required field, and whether it must match a specific pattern (for example, a phone number).
To add a constraint, right-mouse-click on the field and choose Edit Constraints. You may also double click anywhere in the field's row.
The constraints dialog is displayed where you can specify multiple constraints on the field: