What ensures that controls provide valid values in a form?

The concept of validation in both design mode and at runtime is critical in ensuring that controls in a form deliver valid values. When validation is implemented during the design phase, developers can define constraints and rules that are visually incorporated into the user interface. This proactive approach allows for an intuitive design that guides users towards correct input values, reducing the risk of invalid data entry.

Additionally, runtime validation acts as a safeguard when the form is in use, checking for compliance with the defined rules as the user interacts with the form. This dual-layer of validation ensures that any invalid input is caught either when the form is being created or during its actual use, thus enhancing the reliability and integrity of the data collected through the form.

On the other hand, while runtime-only checks serve a purpose, they lack the preventive measures which design-time validation provides. The use of default values can help guide users, but it doesn’t inherently validate user input. Similarly, conditional visibility settings manage the display of certain elements but do not contribute to the validity of the values entered. Therefore, the comprehensive approach of validating in both design mode and at runtime is crucial for ensuring that the values entered into forms are valid and meet specified criteria.