On the chief factors of maximal parabolic subgroups of twisted classical groups

For the finite simple groups of twisted Lie types $^2A_l$ and $^2D_l$, we specify the description for the chief factors of a maximal parabolic subgroup which are involved in its unipotent radical. We prove a theorem in which, for every maximal parabolic subgroup of the groups $^2A_l(q^2)$ and $^2D_l(q^2)$ , we give the fragments of the chief series involving in the unipotent radical of this parabolic subgroup. The generators of the corresponding chief factors are presented in tables.