Indicator 01
Indicator 01 : (1) (Chem) A substance that changes color at a definite hydrogen ion (or other specific ion) concentration; e. g. , litmus, starch, etc. (2) (Fire Pr) A recording instrument for the pressure-volume relationship in an engine. (3) (Metrol) a. Any meter or instrument that shows a physical value, such as temperature, pressure, etc. b. (Brit) A device that visually signals a fire alarm or other warning