The scope of this standard is to address the unit/plant demand development subsystem for boilers with steaming capacities of 200,000 lbs/hr (25 kg/s) or greater. This subsystem includes generation demand, boiler demand development, turbine demand development, throttle/header pressure control, and unit megawatt/steam flow control as applicable. This standard will address two types of process applications: a) a single boiler supplying a single turbine, typical of an electric utility power plant; and b) a single boiler or multiple boilers supplying a common distribution header, typical of an industrial power plant. Specifically excluded from consideration are: a) dispatch control; b) turbine/generator control (other than turbine demand); c) feedwater controls d) steam temperature controls (covered separately by ANSI/ISA-77.44.01, Fossil Fuel Power Plant - Steam Temperature Controls); e) combustion controls (covered separately by ANSI/ISA-77.41.01, Fossil Fuel Power Plant Boiler Combustion Controls); f) steam distribution control systems; g) economic loading of boilers; and h) fluidized bed boilers. Purpose The purpose of this document is to establish the minimum requirements for the functional design specifications of unit/plant demand development for control systems for fossil-fueled power plant boilers.