  We propose a universal approximation of the equation of state of superdense
matter in neutron star (NS) interiors. It contains only two parameters, the
pressure and the density at the center of the maximally massive neutron star.
We demonstrate the validity of this approximation for a wide range of different
types of equations of state, including both baryonic and hybrid models.
Combined with recently discovered correlations of internal (density, pressure,
and speed of sound at the center) and external (mass, radius) properties of a
maximally massive neutron star, this approximation turns out to be an effective
tool for determining the equation of state of superdense matter using
astrophysical observations.
