What does the capacitor and discharge resistance (150pF-330Ω) in IEC 61000-4-2 assume?

What does the capacitor and discharge resistance (150pF-330Ω) in IEC 61000-4-2 assume?

It assumes the ESD phenomenon from a charged human body to electronic equipment. 150pF: Capacitance between the human body and the floor 330Ω: Human body touching with a metal object