  Based on the nuclear attenuation data obtained by the HERMES experiment on
nitrogen and krypton nuclei, it is shown that the nuclear attenuation $R_M^{h}$
can be parametrised in a form of a linear polynomial $P_1=a_{11}$ + $\tau
a_{12}$, where $\tau$ is the formation time, which depends on the energy of the
virtual photon $\nu$ and fraction of that energy $z$ carried by the final
hadron. Three widely known parameterizations for $\tau$ were used for the
performed fit. The fit parameters $a_{11}$ and $a_{12}$ do not depend on $\nu$
and $z$.
