3.3.5.2.2.5 Sending a Get Device Capability Request
The server MUST send the GET_DEVICE_CAP_REQ request message in response to a printing subsystem query to the virtual printer driver for a specific device request. The content for the DeviceCap field is provided by the printing subsystem to indicate what capability is requested. The DevmodeIn field content is also provided by the printing subsystem to indicate a DEVMODE for the virtual printer driver. The InputBufferSize field indicates the maximum returned data size for the OutputBuffer field in the response.