  Gamma Ray Bursts (GRB) observed up to redshifts $z>8$ are fascinating objects
to study due to their still unexplained relativistic outburst mechanisms and a
possible use to test cosmological models. Our analysis of 77 GRB afterglows
with known redshifts revealed a physical subsample of long GRBs with canonical
{\it plateau breaking to power-law} light curves with a significant {\it
luminosity $L^*_X$ - break time $T^*_a$} correlation in the GRB rest frame.
This subsample forms approximately the {\it upper envelope} of the studied
distribution. We have also found a similar relation for a small sample of GRB
afterglows that belong to the intermediate class (IC) between the short and the
long ones. It proves that within the full sample of afterglows there exist
physical subclasses revealed here by tight correlations of their afterglow
properties. The afterglows with regular (`canonical') light curves obey not
only a mentioned tight physical scaling, but -- for a given $T^*_a$ -- the more
regular progenitor explosions lead to preferentially brighter afterglows.
