xPL Game Port Interface
The joystick port found on many modern sound cards is an inexpensive way of connecting up to 8 input devices to your PC. These can include light and temperature sensors, PIRs, switches and so on.
The xPL Game Port Interface transmits xPL messages containing the data read back from devices connected to the joystick port, allowing other xPL-enabled devices to act on the data.
Messages conform to the joystick.basic schema.