  Motivated by the recent determination of the top quark mass by the CDF
collaboration, $\mt =174 \pm 10 ^{+13}_{-12}$ GeV, we review and update the
constraints on the parameters of the quark flavour mixing matrix $V_{CKM}$ in
the standard model. In performing our fits, we use inputs from the measurements
of the following quantities: (i) $\abseps$, the CP-violating parameter in $K$
decays, (ii) $\delmd$, the mass difference due to the \bdbdbar\ mixing, (iii)
the matrix elements $\absvcb$ and $\absvub$, and (iv) $B$-hadron lifetimes. We
find that the allowed region of the unitarity triangle is very large, mostly
due to theoretical uncertainties. (This emphasizes the importance of
measurements of CP-violating rate asymmetries in the $B$ system.) Nevertheless,
the present data do somewhat restrict the allowed values of the coupling
constant product $f_{B_d}\sqrt{\hat{B}_{B_d}}$ and the renormalization-scale
invariant bag constant $\hat{B}_K$. With the updated CKM matrix we present the
currently-allowed range of the ratio $\vert V_{td}/V_{ts} \vert$, as well as
the standard model predictions for the \bsbsbar\ mixing parameter $\xs$ and the
quantities $\sin 2\alpha$, $\sin 2\beta$ and $\sin^2\gamma$, which characterize
the CP-asymmetries in $B$-decays. The ALEPH collaboration has recently reported
a significant improvement on the lower limit on the $\bs$-$\bsb$ mass
difference, $\Delta M_s/\Delta M_d > 11.3$ (95\% C.L.). This has interesting
consequences for the CKM parameters which are also worked out.
  NOTE: this is a revised and updated version of our previous paper.
