[Users] reduction operation in CarpetIOScalar

Hi, I'm concerning about how outscalar_reductions (e.g. one of its default, sum) in the thorn CarpetIOScalar counting values on carpet grid with multiple refinement levels. The output section in the gallery parfile nsnstohmns.par has one line reading IOScalar::outScalar_vars="...(e.g. HydroBase::rho)", so does it count values on a specified refinement level and is the counting different among different outscalar_vars? I also wonder what does "icount iaverage inorm" mean in outscalar_reductions' default. Thanks in advance for your help! Yours sincerely, Jimmy