When constructing a map of simplicial modules, this option specifies the degree $d$ of the resulting map. A map of degree $d$ consists of component maps $f_i : C_i \to D_{i+d}$. By default, the degree is 0.
The source of this document is in /__w/M2/M2/macaulay2-1.26.05+ds/M2/Macaulay2/packages/SimplicialModules/SimplicialModuleDOC.m2:4140:0.