On the span of lattice points in a parallelepiped

Let $\mathrm{\Lambda }\subset {\mathbf{R}}^n$ be a lattice which contains the integer lattice ${\mathbf{Z}}^n$. We characterize the space of linear functions ${\mathbf{R}}^n\to \mathbf{R}$ which vanish on the lattice points of $\mathrm{\Lambda }$ lying in the half-open unit cube $[0,1{)}^n$. We also find an explicit formula for the dimension of the linear span of $\mathrm{\Lambda }\cap [0,1{)}^n$. The results in this paper generalize and are based on the Terminal Lemma of Reid, which is in turn based upon earlier work of Morrison and Stevens on the classification of four dimensional isolated Gorenstein terminal cyclic quotient singularities.