  We construct "MV squares" in the category $\mathbf{MCor}$ of modulus pairs
which was introduced in arXiv:1511.07124 [math:AG]. They allow us to describe
the category $\mathbf{MDM}_{\mathrm{gm}}^{\mathrm{eff}}$ of loc. cit. in a
similar way as Voevodskys category $\mathbf{DM}_{\mathrm{gm}}^{\mathrm{eff}}$,
thus sharpening the results of the quoted paper.
