Three classes of nonlinearly interacting triads, whose wave numbers and frequencies satisfy K1¿K2=K3 and ω1¿ω2=ω3, dominate the numerically computed transfer of energy in the Garrett and Munk models of the oceanic interval wave spectrum. We designate these triads as induced diffusion, elastic scattering, and parametric subharmonic instability. Special characteristics of wave number and frequency among the components identify each triad class. The concepts represented by these classes simplify an otherwise complex process and help explain some of the basic features of the observed internal wave spectrum.