  We employ implicit regularization (IReg) in quark-antiquark decays of the Z,
or of a scalar (CP-even or odd) boson at NLO, and compare with dimensional
schemes to reveal subtleties involving infrared divergence cancellation and
$\gamma_5$-matrix issues. Besides the absence of evanescent fields in IReg,
such as $\epsilon$-scalars required in certain schemes that operate partially
in the physical dimension, we verify that our procedure preserves gauge
invariance in the presence of the $\gamma_5$ matrix without requiring symmetry
preserving counterterms while the amplitude is infrared finite as required by
the KLN theorem.
