ISO 31-4

ISO 31-4 is the part of international standard ISO 31 that defines names and symbols for quantities and units related to heat. It is superseded by ISO 80000-5.

Its definitions include:

Quantity		Unit			Remarks
Name	Symbol	Name	Symbol	Definition
thermodynamic temperature	T, (Θしーた)	kelvin	K	The kelvin is the fraction 1/273.16 of the thermodynamic temperature of the triple point of water.	For practical measurements, the International Temperature Scale of 1990 defines several fixed points and interpolation procedures.
Celsius temperature	t, φふぁい	degree Celsius	°C	The degree Celsius is a special name for the unit kelvin, for use in stating values of Celsius temperature.	t = T − T0, where T0 = 273.15 K
linear expansion coefficient	αあるふぁl	reciprocal kelvin, kelvin to the power negative 1	K−1		$\alpha _{l}={\frac {1}{l}}{\frac {l}{T}}$
...

Annex A of ISO 31-4 lists units of heat based on the foot, pound and second and some other units, including the degree Rankine, degree Fahrenheit, British thermal unit and others. Annex B lists conversion factors for three versions of the calorie.