Concerning difference matrices (Q1924171)

An \((s,v;\lambda)\)-difference matrix over the group \((G,*)\) of order \(s\) is a \((v\times s\lambda)\)-matrix \(D\) with entries from \(G\) such that for any two rows \(i_1\) and \(i_2\) of \(D\), \(d(i_1,j)*\{d(i_2,j)\}^{-1}\) for \(j=1,2,\dots,s\lambda\) contains each element of \(G\) exactly \(\lambda\) times. Difference matrices can be expanded to orthogonal arrays. Several new constructions of difference matrices are given.