The deviceType field of a device data structure (of type TQADevice ) specifies a device type. You use these constants to assign a value to that field.
typedef enum TQADeviceType {
kQADeviceMemory = 0,
kQADeviceGDevice = 1,
kQADeviceWin32DC = 2,
kQADeviceDDSurface = 3
} TQADeviceType;