Subconstituents of symplectic graphs modulo pn

The two subconstituents of symplectic graphs modulo ), where ν,n are positive integers, are studied. The first subconstituent is shown to be a 3-Deza graph except the trivial case ν=1, when it is strongly regular. And when ν⩾2, the second subconstituent is shown to be a strictly Deza graph. The parameters of these graphs are determined. Moreover, the chromatic number and the full automorphism group of these two subconstituents are given.