  We have made a series of joint spectral fits for two blank fields, the
Lockman Hole and the Lynx-3A field, where a significant amount of both ASCA and
ROSAT PSPC data exist after thorough screenings. The ASCA SIS, GIS and ROSAT
PSPC spectra from these fields have been fitted simultaneously. Comparison at
E>1$keV shows general agreement within 10% in the Lockman Hole data and a
20-30% disagreement in the Lynx-3A data, indicating remaining
observation-dependent systematic problems. In both cases, satisfactory fits
have been found for the overall 0.1-10 keV spectrum with an extragalactic
power-law component (or a broken power-law component with steepening at E<1
keV), a hard thermal component with plasma temperature of kT\approx 0.14 keV
and a soft thermal component kT\approx 0.07 keV.
