  Aiming to delineate the physical framework of blazars, we present an
effective method to estimate four important parameters based on the idea
proposed by \citet{BK95}, including the upper limit of central black hole mass
$M$, the Doppler factor $\delta$, the distance along the axis to the site of
the $\gamma$-ray production $d$ (which then can be transformed into the
location of $\gamma$-ray-emitting region $R_{\gamma}$) and the propagation
angle with respect to the axis of the accretion disk $\Phi$. To do so, we adopt
an identical sample with 809 {\it Fermi}-LAT-detected blazars which had been
compiled in \citet{Pei20PASA}. These four derived parameters stepping onto the
stage may shed new light on our knowledge regarding $\gamma$-ray blazars. With
regard to the paper of \citet{BK95}, we obtain several new perspectives, mainly
in: (1) putting forward an updated demarcation between BL Lacs and FSRQs based
on the relation between broad-line region luminosity and disk luminosity both
measured in Eddington units, i.e., $L_{\rm disk}/L_{\rm
Edd}=4.68\times10^{-3}$, indicating that there are some differences between BL
Lacs and FSRQs on the accretion power in the disk; (2) proposing that there is
a so-called `appareling zone', a potential transition field between BL Lacs and
FSRQs where the changing-look blazars perhaps reside; (3) the location of
$\gamma$-ray emission region is principally constrained outside the broad-line
region, and for some BL Lacs are also away from the dusty molecular torus,
which means the importance of emission components in the jet.
