 The model year might of a product is a number used worldwide, but with a high level of prominence in North America, to describe the proximately when a product was produced, and it usually indicates the coinciding based specification design revision number of that product. The model year and the actual calendar year of production rarely coincide. For example, the North American 2015 model year automobile is available during most of the 2015 calendar year, but is usually also available from the third quarter of 2014 because production of the 2015 model began in July or August 2014, continuing to May-June-July 2015. The variables of build date and design revision number are semi-independent. There is no natural law that forces one to be strictly correlated to the other, other than that. Later design revisions cannot have been built in the past, and most products, in most contexts, tend to be built to the design revision that was the latest one at the time of building.