This Aerospace Standard covers two basic types of temperature instruments as follows:

TYPE I: Ratiometer type, actuated by changes in electrical resistance of a temperature sensing electrical resistance element; the resistance changes being obtained by temperature changes of the temperature sensing resistance element.

TYPE II: Millivoltmeter type, operated and actuated by varying E.M.F. output of a thermocouple; the varying E.M.F. input to the instrument being obtained by temperature changes of the temperature sensing thermocouple.