**MSC:**- 41A25 Rate of convergence, degree of approximation
- 41A30 Approximation by other special function classes

of a finite set of functions $\f_{\nu}$ $(\nu=0, \ldots , r-1)$ which are

not necessarily compactly supported, but have a suitable decay rate.

Assuming that the function vector $\ff= (\f_{\nu})_{\nu=0}^{r-1}$ is

refinable, we sketch a new way, how to derive

necessary and sufficient conditions for the refinement mask

in Fourier domain.