  We present a study of the physical plasma parameters such as electron
temperature, electron density, column depth and filling factors in the moss
regions and their variability over a short (an hour) and a long period (5
consecutive days) of time. Primarily, we have analyzed the spectroscopic
observations recorded by the Extreme-ultraviolet Imaging Spectrometer (EIS)
aboard Hinode. In addition we have used supplementary observations taken from
TRACE and the X-Ray Telescope (XRT). We find that the moss emission is
strongest in the Fe xii and Fe xiii lines. Based on analyses using line ratios
and emission measure we found that the moss region has a characteristic
temperature of log T = 6.2. The electron densities measured at different
locations in the moss regions using Fe xii ratios are about 1-3\times1010
cm(-3) and about 2-4\times10^9 cm^(-3) using Fe xiii and Fe xiv. The electron
density substantially increases (by a factor of about 3-4 or even more in some
cases) when a background subtraction was performed. The density and temperature
show very small variation over time. The filling factor of the moss plasma can
vary between 0.1-1 and the path length along which the emission originates is
from a few 100 to a few 1000 kms long. By combining the observations recorded
by TRACE, EIS and XRT, we find that the moss regions correspond to the
foot-points of both hot and warm loops.
