  Using the CLEO II detector operating at the CESR e+e- collider, we have
measured the structure functions in the decay tau+/- --> pi+/- pi0 pi0 nu,
based on a sample corresponding to 4*10E6 produced tau-pair events. We
determine the integrated structure functions, which depend only on the three
pion invariant mass, as well as the structure functions differential in the
Dalitz plot. We extract model independent limits on non-axial-vector
contributions from the measured structure functions as less than 16.6% of the
total branching fraction, at the 95% confidence level. Separating the
non-axial-vector contributions into scalar and vector contributions, we measure
that scalars (vectors) contribute with less than 9.4% (7.3%) to the total
branching ratio, at the 95% confidence level.
