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. |