Hidden integrable hierarchies of AKNS type

A method for constructing integrable hierarchies by restricting AKNS flows on manifolds of finite codimension in the space of independent parameters i s provided. Two particular types of hierachies are characterized: one is gi ven by nonlinear differential equations with coordinate-dependent coefficie nts and the other is related to Schrodinger spectral problems with energy-d ependent potentials of even degree.