A liquid proving system is provided with a small volume liquid prover draining into a liquid holding tank that has capacity for multiple proving measurements. The orthosis provides stable support of the forearm about a horizontal plane, while enabling both pivotal movement of the arm about a vertical axis intersecting the patient’s elbow and towards or away from the patient’s torso within this horizontal plane. The rendering package receives data representative of the scene to be represented graphically, and converts that data into rasterised image data. The card receives a test signal from a test device and supplies the test signal simultaneously to these semiconductor integrated circuits arranged in two columns and at least tow rows, through the groups of probe needles. According to one embodiment, the guide structure of the present invention is retro-fitted to an existing mouse by the use of a peel and stick adhesive.