An internal auditor observed that sales staff are able to modify or cancel an order...

Application controls are specific to software applications and ensure that transactions are processed correctly and accurately. They include controls over input, processing, and output. In this scenario, examining application controls will help determine if sales staff can modify orders after shipping, as these controls directly impact how data is handled within the system.

References:

"Information Technology Auditing," which explains the role of application controls in maintaining data integrity and security.