An automotive alternator includes a rear frame having a rear end wall and a cover member covering a brush device. Each source-destination address pair is assigned a counter for tracking respective acknowledgements to messages output via the corresponding source-destination address pair. The user device performs a determination process of determining whether data corresponding to property definition data in the property selection list is present in the property list, and performs a content use eligibility determination process in accordance with a decision process sequence of a next process step based on a process setting code accompanying the property definition data.