Operating System Model
An SDV operating system model or harness consists of partial and abstracted segments of Windows code that act as the operating system during a verification. SDV includes a default operating system model and several specialized models that are used to verify particular rules. SDV assembles the operating system model for a verification during the Check step of the verification process.
There is also a harness that executes parts of your driver in the same manner as the Windows Operating System by calling into entry points in the driver.