Section SCNseries.
Variables A : {group gT}.
Hypothesis SCN_A : A \in 'SCN(G).
Let Z := 'Ohm_1(A).
Let cAA := SCN_abelian SCN_A.
Let sZA: Z \subset A := Ohm_sub 1 A.
Let nZA : A \subset 'N(Z) := sub_abelian_norm cAA sZA.

(* This is Aschbacher 23.15(2). *)
Lemma der1_stab_Ohm1_SCN_series : ('C(Z) :&: 'C_G(A / Z | 'Q))^`(1) \subset A.