Related terms
A constraint is a comparative relationship between property values (or between a property value and a constant or expression) that is expected to be true at all times.
For example, your application may require that an interest rate entered by a user be no less than 4.25 percent and no greater than 9.00 percent.
You can record constraints in your application using constraints rules, a type of declarative rule defined by the Rule-Declare-Constraints class. Constraints rules are evaluated when the value of any property mentioned in the rule changes. If a constraint is not met, the page containing the property is marked with a message, making the page invalid.