H vs. HFORM(IS)

mspark

Hi all

According to the NOMENCLATURE FOR USER-CODED SUBROUTINES, there are two parameter related to enthalpy.

These are H and HFORM(IS). H is specific enthalpy. HFORM(IS) is specific enthalpy of formation of species IS (J/kg).

what are difference between them, and when do i use HFORM(IS).

regards

mspark