Structured validation allows for the combination of any of various basic data type validation steps, along with more complex processing.
Such complex processing may include the testing of conditional constraints for an entire complex data object or set of process operations within a system.
For example, many database systems allow the specification of the following l (plus, minus, and parentheses).
A more sophisticated data validation routine would check to see the user had entered a valid country code, i.e., that the number of digits entered matched the convention for the country or area specified.
Whether a grade is correct can only be established by clerical checks or by reference to other files.
During systems design, therefore, data definitions are established which place limits on what constitutes valid data.
A judgement as to whether data is valid is made possible by the validation program, but it cannot ensure complete accuracy.
It uses routines, often called "validation rules" "validation constraints" or "check routines", that check for correctness, meaningfulness, and security of data that are input to the system.
The Post-validation action sends feedback to help enforce validation.