  This paper is devoted to the use of half-form bundles in the symbolic
calculus of Berezin-Toeplitz operators on Kahler manifolds. We state the
Bohr-Sommerfeld conditions and relate them to the functional calculus of
Toeplitz operators, a trace formula and the characteristic classes in
deformation quantization. We also develop the symbolic calculus of Lagrangian
sections, with the crucial estimate of the subprincipal terms.
