PROPATH: A Program Package for Thermophysical Properties of Fluids. PROPATH is a subroutine/function type computer program package for thermophysical properties of fluids written by FORTRAN77, with which one can get thermophysical properties quite easily on referring these subroutines and/or functions from his/her FORTRAN main program unit like the trigonometric functions. Single shot programs through which a user can find properties on his/her computer display point by point interactively are prepared as well. In addition, some PROPATH functions can also be referred to as functions of Microsoft EXCEL97(E-PROPATH).