When you define rules for tables, those rules apply when you import data.
Adobe provided a lot of infrastructure to do that with just a simple script.
For more information about data types, field sizes, and input masks, see the article Introduction to data types and field properties.
You can define validation rules for table fields and for controls on forms.
As I mentioned before, information is passed to the validation function in the event object, and in the code we see that the member ‘value’ is used to communicate the current value of the field.
The member ‘rc’ (or return code) is used to communicate back if the validation was successful or not.