Discontinuities, Feynman parameters and d-lines

The calculation of asymptotic limits of Feynman diagrams using Feynman parameter techniques has developed a powerful and useful technology. A major gap in this armory has concerned the calculation of specific discontinuities of Feynman diagrams. The author remedies this gap and illustrates the new technique on a series of familiar situations. These include in the Regge limit, the ladder and the AFS diagrams, and the x approximately 1 deep inelastic electroproduction region. (4 refs).