When an operating state indicated by a set of operation data measured during normal operation becomes a state satisfying an operation data obtaining condition, the set of operation data at the time is obtained as a set of operation data for initial learning, and an inner volume of a refrigerant extension piping is calculated based on the obtained set of operation data for initial learning. Actual play is controlled through selectively accessing a particular displayed keyframe. The system comprises a pipe of compliant material extending helically around and thermally conductively coupled, preferably adhesively bonded, to the support body and serving to conduct liquid coolant for heat exchange with the body over substantially all the external circumferential surface thereof. Digital audio and video files stored on a storage device are often included with the manuscript. In addition to the centrally mounted engine, the pivotal mount of the extensible boom is elevated from the frame to allow a forklift operator complete visibility of the terrain surrounding the forklift. The process measures a value representative of the volume of lubricating oil in the internal combustion engine and detects an entry of fuel into the lubricating oil on the basis of an evaluation of results of the measurement which were obtained for different points in time.