Comment: Proceedings of the 11th Silpakorn University Research Fair, Silpakorn University, Thailand (2019)This work critics on nature of thermodynamics coordinates and on roles of the variables in the equation of state (EoS). Coordinate variables in the EoS are analyzed so that central concepts are noticed and are used to lay a foundation in building of a new EoS or in testing EoS status of a newly constructed empirical equation. With these concepts, we classify EoS into two classes. We find that the EoS of market with unitary price demand and linear price-dependent supply function proposed by \cite{GumjMarket}, is not an EoS because it has only one degree of freedom.