The most common example of programmed controls over the accuracy and completeness of input are edit (data validation) checks when the software checks that data fields included on transactions by performing:
reasonableness check, eg net wage to gross wage
existence check, eg that a supplier account exists
character check, eg that there are no alphabetical characters in a sales invoice number field
range check, eg no employee’s weekly wage is more than $2,000
check digit, eg an extra character added to the account reference field on a purchase invoice to detect mistakes such as transposition errors during input.
When data is input via a keyboard, the software will often display a screen message if any of the above checks reveal an anomaly, eg ‘Supplier account number does not exist’.