THE PROCESS $e^{+}{e}^{-}\to l\bar{l}q\bar{q}$ AT LEP AND NLC

The cross sections for the reaction $e^{+}{e}^{-}\to l\bar{l}q\bar{q}$ and for similar four fermion production processes at LEP~1, LEP~2 and the NLC are calculated. Due to the extraordinary symmetry properties of the process, very compact analytical formulae describe the double differential distributions in the invariant masses of the $l\bar{l}$ and $q\bar{q}$ pairs. The total cross sections may be obtained with two numerical integrations.