New quantum numbers in collision theory

A set of indices {σ,τ,ζ,η} is introduced to replace the four orbital quantum numbers that occur in cross-section formulas. Each index belongs to a different species of a $C_{2v}$ point group; only σ ranges to infinity whereas all four orbital l’s do. Results of an earlier calculation are restructured in terms of {σ,τ,ζ,η} affording an improved interpretation of those results. Directions of further investigation are indicated.