“…is an increasing sequence of ordinal numbers and symbols ∞ satisfying the following condition: if between σ n and σ n+1 there is a jump, then in A there is an element of order p and height σ n (see [3,Theorem 67.1]]. Also, with the use of terms of the indicator and full transitivity, the lattice of the fully invariant subgroup was studied for some classes of torsion-free mixed and p-groups by Baer [1], Göbel [4], Grinshpon and Krylov [6], Kaplansky [7], Linton [10], Mader [11], Misyakov [13], Moore and Hewet [14], Moskalenko [15], Piere [16], and others. Little is known on the lattice of fully invariant subgroups in the class of cotorsion groups.…”