The definition of special controlling process parameters or known military or other specifications are needed when special heat treating procedures are required on purchase/work orders. An example of a process parameter statement: “Process temperature of 1900°F +/- 25°F required.” This parameter places the set point of the furnace at exactly 1900°F and the uniformity of the furnace heat zone is +/- 25°F. This parameter does not mean that the furnace set point may be between 1875°F and 1925°F. The definition of the temperature, and measurement scale, Fahrenheit or Centigrade, is required.