  We show that the Stephenson-Kilmister-Yang (SKY) equation combined with
Camenzind's matter current term naturally provides the cosmological constant
and dark radiation as integration constants of the SKYC field equation. To
characterize the property of the dark radiation, we develop a method to
separate it from the ordinary radiation. We found a special property of
Camenzind's matter current, namely that the solution space for radiation in
fact belongs to that of the vacuum solution of SKY equation. We also found that
his matter current does not obey the conservation condition suggested by
Kilmister. Finally, we discuss the possible role of dark radiation emergent
from the SKYC theory in recent cosmic-microwave-background observations and its
implications to the inflation scenario.
