  In this paper we shall prove that every Witten multiple zeta value of weight
w>3 attached to sl(4) at nonnegative integer arguments is a finite rational
linear combinations of MZVs of the weight w and the depths three or less,
except for the nine irregular cases where the Riemann zeta value zeta(w-2) and
the double zeta values of weight w-1 and depth <3 are also needed.
