  Berry-Robnik level spacing distribution is demonstrated clearly in a generic
quantized plane billiard for the first time. However, this ultimate
semi-classical distribution is found to be valid only for extremely small
semi-classical parameter (effective Planck's constant) where the assumption of
statistical independence of regular and irregular levels is achieved. For
sufficiently larger semiclassical parameter we find (fractional power-law)
level repulsion with phenomenological Brody distribution providing an adequate
global fit.
