For instance, in the case of the scalar there are two tensors in the basis unlike the unique one of the RI${}^\prime$ scheme. In this case the additional basis element is $\Gamma_{(2)}^{pq}$ where we use the convention that the appearance of a momentum vector in place of a Lorentz index indicates the contraction of that index with that momentum. Clearly this object vanishes if either momentum is zero or one is proportional to the other, corresponding to the RI${}^\prime$ scheme momentum configuration. As regards the tensor basis for each of the operators, the use of the generalized matrices $\Gamma_{(n)}^{\mu_1 \ldots \mu_n}$ is important in regarding the basis as complete. This is because they span spinor space in $d$-dimensions, [@37; @39], with $n$ being any positive integer. Therefore, it is natural to make use of them in dimensionally regularized computations. Though for the operators considered here $n$ never exceeds $4$. If there were more than two independent momenta then obviously a larger value of $n$ would be necessary. As $\Gamma_{(n)}^{\mu_1 \ldots \mu_n}$ clearly form the basis of the spinor vector space of the tensor basis decomposition, the Lorentz vector space part of the overall basis for each operator is then made 