### Modify a Module Definition File for Virtual Device Drivers

When you link your virtual device driver, you must use a module definition (`.DEF`) file. The first statement in the file must be

       VIRTUAL DEVICE device_name

where device_name specifies the name of the VDD. The file cannot contain a `NAME` statement.

Once you have created your device driver, you must place a DEVICE statement in your CONFIG.SYS file to ensure it is treated as a device by the operating system.

Developing Virtual Device Drivers in OS/2

Virtual Device Driver Calling Conventions
Summary of Module Definition Statements