  Our first very wide survey of the supercritical phase diagram and its key
properties using molecular dynamics simulations reveals a universal
interrelation between dynamics and thermodynamics and a transition between
liquidlike and gaslike states. This is seen in the master plot showing a
collapse of the data representing the dependence of specific heat on key
dynamical parameters in the system for many different paths on the phase
diagram. As a result, the observed transition is path-independent and occurs at
many hundred times the critical pressure and temperature. We call it a
"c"-transition due to the "c"-shaped curve parametrising the dependence of the
specific heat on key dynamical parameters. The "c"-transition provides a new
structure to the phase diagram. On the basis of path independence and the
existence of a special inversion point on the phase diagram, we conjecture the
existence of a new phase transition in deeply supercritical state
