2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/117759We study modularity of the lattice Lat $(T)$ of closed invariant subspaces for a $C_0$-operator $T$ and find a condition such that Lat $(T)$ is a modular. Furthermore, we provide a quasiaffinity preserving modularity.12 pagesK-Theory and Homology42B30, 42B35, 17C65, 51D25text