  The linear drift-tearing mode is analyzed for different regimes of the
plasma-$\beta$, ion-skin-depth parameter space with an unreduced, extended-MHD
model. New dispersion relations are found at moderate plasma $\beta$ and
previous drift-tearing results are classified as applicable at small plasma
$\beta$. The drift stabilization of the mode in the regimes varies from
non-existent/weak to complete. As the diamagnetic-drift frequency is
proportional to the plasma $\beta$, verification exercises with unreduced,
extended-MHD models in the small plasma-$\beta$ regimes are impractical. The
new dispersion relations in the moderate plasma-$\beta$ regimes are used to
verify the extended-MHD implementation of the NIMROD code [C. R. Sovinec et
al., J. Comput. Phys. 195, 355 (2004)]. Given the small boundary-layer skin
depth, discussion of the validity of the first-order finite-Larmour-radius
model is presented.
