GOTCHA: Mathematica v13.2+: Operations on "DegreesFahrenheit" °F and "DegreesCelsius" °C are now performed using Kelvins (K). CASE: Naive percentage operation gives answer relative to Kelvins. Use "DegreesCelsiusDifference"/"DegreesFahrenheitDifference"!
GOTCHA: Mathematica: Specific enthalpy conversion J/kg to Btu/lb: Does not consider a possible "total" enthalpy reference offset vs 0 °C or 0 °F respectively
Wolfram SystemModeler: On Mac the Unit Conversions dialog is under SystemModeler -> Preferences -> Global -> Unit Conversion (rather than under Tools -> Options)
Wolfram SystemModeler: GOTCHA: The conversion dialog will not offer the Add Unit Conversion button unless there is not already an existing conversion in BOTH directions.
