American Society of Mechanical Engineers, learn more at https://www.asme.org/
Heat required to change state, but not temperature. (example: the heat to change an ice cube to a liquid, but the temperature does not change)
Heat that causes a temperature change, the warmth that you feel from the sun or from a campfire.
Shift operator is a person who is responsible for operation of the boilers for a set period of time during their shift, where a person in charge of boilers is responsible for the overall operation of the boilers.