97-01E

Convexity of multifractal spectra seems to contradict general field theoretic arguments showing that power of field operators $\phi ^f$ yield a concave spectrum of exponents as function of $f$. This is resolved by appropriate choice of operators to describe multifractal moments. In a Lagrangian field theory of two mutually interacting species of fields $\phi ,\psi $, operators $O_{f'f}=\psi ^{f'}\phi ^f$ with traceless symmetry give rise to multifractal spectra of harmonic diffusion near absorbing fractals when evaluated for zero component fields.