The JDD_GETDEVCAPS message requests information about the coordinate range and button configuration of a device. In response to this message, the driver fills in the JOYCAPS structure, which is described in the Win32 SDK.. (A pointer to it is passed to the lParam1 parameter.) The JOYCAPS structure contains information that describes the coordinate range, button configuration, and manufacturer of the device.
The minimum and maximum position values should reflect a set of logical coordinates that is independent of minute differences between copies of a hardware device. For example, users of joystick services should always see a full range of logical coordinates returned from a calibrated joystick. Calibration values should not affect the minimum and maximum values returned by a driver.
If a hardware device does not support a given axis, return zero values for the minimum and maximum coordinate values for that axis. For example, a driver for a two-dimensional device would set the wZmin and wZmax members of the JOYCAPS structure to zero.