Implementation of the Leibbrandt-Mandelstam gauge prescription in the null-plane bound-state equation

In gauge theories in a null-plane gauge, infinities can arise from the $\frac{1}{n}·q$ singularity in the gauge boson propagator. Leibbrandt and Mandelstam have given a prescription for defining this singularity so as to give finite results for the four-dimensional loop integrals in Feynman diagrams. However, this prescription is not directly applicable to calculations based on $x^{+}$ ordered perturbation theory, and in particular to the the null-plane bound-state equation. We show how the prescription can be applied in the simplest version of this kind of calculation.