  Tests of the Lorentz structure of t --> W b decay will be carried out at the
Tevatron, and later at the LHC and at a NLC. To quantitatively assay future
measurements of competing observables, we consider the (V-A) coupling values of
the helicity decay parameters versus "(V-A) + Single Additional Lorentz
Structures". Three phase-type ambiguities exist, but measurement of the sign of
the large interference between the W boson longitudinal/transverse amplitudes
could exclude the two due dynamically to additional (S+P) and (f_M + f_E)
couplings. Sizable T-violation signatures can occur for low-effective mass
scales, < 320 GeV, but in most cases can be more simply excluded by 10%
precision measurement of the probabilities P(W_L) and P(b_L). Signatures for
the presence of T-violation associated with the dynamical phase-type
ambiguities, CP-violation signatures, and Lambda_b polarimetry are also
discussed.
