In general, the various models of socialist economic planning such as a socialist mode of production exist as theoretical constructs that have not been implemented fully by any economy, partially because they depend on vast changes on a global scale. In the context of mainstream economics and the field of comparative economic systems, socialist planning usually refers to the Soviet-style command economy, regardless of whether or not this economic system actually constituted a type of socialism or state capitalism or a third, non-socialist and non-capitalist type of system.