The theoretical prices of electricity at each node on the network is a calculated "shadow price", in which it is assumed that one additional kilowatt-hour is demanded at the node in question, and the hypothetical incremental cost to the system that would result from the optimized redispatch of available units establishes the hypothetical production cost of the hypothetical kilowatt-hour. This is known as "locational marginal pricing" (LMP) or "nodal pricing" and is used in some deregulated markets, most notably in the Midcontinent Independent System Operator, PJM Interconnection, ERCOT, New York, and New England markets in the United States, New Zealand, and in Singapore.