There are several types of changes within the Monitoring and Controlling Phase of a project:
1. Non-Essential Design Change (NDC): Change to a design control document while product is still in design control
2. Design Change Number (DNC): Major change to device’s Bill of Materials or other manufacturing document while device is still in design controls
3. Engineering Change Order (ECO): Change to a device after design controls are finished. Sometimes is can be the project itself.

Each of these changes can affect a project differently. Some are done while the design controls are being created and some can create impact afterwards.