Where is the maximum (or minimum)?

Hello.

Does anyone know how to find (not only represent) the coordinates of the max (min) value of a variable, for instance in 3D? I mean, when one plots 'Max/Min Volume' (in a 3D Plot Group / More Plots), the maximum and minimum values of the chosen variable are shown graphically as points, but how to know their cartesian coordinates?

Thanks.

Jesus.