  We examine quark flavour mixing matrices for three and four generations using
the recursive parametrization of $U(n)$ and $SU(n)$ matrices developed by some
of us in Refs.[2] and [3]. After a brief summary of the recursive
parametrization, we obtain expressions for the independent rephasing invariants
and also the constraints on them that arise from the requirement of mod
symmetry of the flavour mixing matrix.
