  Using data from the Extreme-ultraviolet Imaging Spectrometer aboard Hinode,
we have studied the coronal plasma in the core of two active regions.
Concentrating on the area between opposite polarity moss, we found emission
measure distributions having an approximate power-law form EM$\propto T^{2.4}$
from $\log\,T = 5.5$ up to a peak at $\log\,T = 6.55$. We show that the
observations compare very favorably with a simple model of nanoflare-heated
loop strands. They also appear to be consistent with more sophisticated
nanoflare models. However, in the absence of additional constraints, steady
heating is also a viable explanation.
