X-based and m-based activity coefficients in the solver

On the molality basis, the activity coefficient of water is undefined (it is defined for all components except water). Therefore, we report directly the activity of water in the γ–m-based column. Water is the only exception (because of the definition of molality, which refers everything to 1 kg of water). For all other components, we report the activity coefficients. On the mole fraction scale, there are no such exceptions because water is then treated as any other component and the γ–x-based column shows activity coefficients for all species, including water. So, xwater(x-based)γwater(x-based) = awater(x-based)=awater(m-based).