  A standard-form Wadati-Konno-Ichikawa(WKI) type integrable hierarchy is
derived from a corresponding matrix spectral problem associated with the Lie
algebra sl(2, R). Each equation in the resulting hierarchy has a bi-Hamiltonian
structure furnished by the trace identity. Then, the higher grading affine
algebraic construction of some special cases is proposed. We also show that
eneralized short pulse equation arises naturally from the negative WKI flow.
