The Data Type dropdown list indicates the data type that the input component is expected to contain. Types such as String, Int32, and Int64 are available, as well as other options such as Decimal and Date.
For the validation of a date, the IFormatProvider is the current thread's date format.
Validation Error Messages and Data Types
When the wrong data type is used in an input component, the message defined in the Data Types tab of the "Default Validation Error Messages for ValidationProvider" dialog is used. If a custom message has been defined for the validation criterion, the message in the "Customize Validation Error Messages for Criterion" dialog is used.
See Also
Setting Up Default Error Messages | Customizing Error Messages