Standard Validation method
This validation method is typically used to restrict the number and type of characters accepted in a field.
For example, a credit card field has exactly 16 characters and the only characters allowed are the digits 0-9. If the data extracted for a field does not meet these criteria, it is presented to a Validation user so they can validate the field.
Additionally, you can restrict numeric characters from a name field, while allowing certain punctuation such as a hyphen for hyphenated names like "Rhys-Jones."
If there is a distinct pattern to the expected extracted data, the best practice is to use a Regular Expression validation method rather than listing all of the allowed characters.