In this paper, we report on an updated, improved version of the MARKAL energy model, developed in the late 1970's under the aegis of member countries of the International Energy Agency. MARKAL is an integrated multi-period linear-programming model of energy systems, characterized by the representation of individual devices and energy carriers at every stage of the extraction, transformation, distribution, and consumption of energy forms. The model is driven by useful demands for goods and services in the economic subsectors. There exists a standard version of MARKAL, and other versions resulting from modifications and additions by individual countries. The Canadian MARKAL model is significantly different from the standard as well as from other versions of MARKAL. It was developed in several stages over the period 1984 to~1989, each stage being motivated by specific applications that could not easily be implemented with the previous model versions. Although some of the features of the Canadian version may have been independently developed by other modellers as well, no single other model contains as many new capabilities.