CGAE[i] can be used as input for \gamma ^i in D-4 dimensions, where i is a
Cartesian index, and is transformed into
DiracGamma[CartesianIndex[i,D-4],D-4] by
FeynCalcInternal.
CGAE[i]\hat{\gamma }^i
CGAE[i, j] - CGAE[j, i]\hat{\gamma }^i.\hat{\gamma }^j-\hat{\gamma }^j.\hat{\gamma }^i
StandardForm[FCI[CGAE[i]]]
(*DiracGamma[CartesianIndex[i, -4 + D], -4 + D]*)CGAE[i, j, k, l]\hat{\gamma }^i.\hat{\gamma }^j.\hat{\gamma }^k.\hat{\gamma }^l
StandardForm[CGAE[i, j, k, l]]
(*CGAE[i] . CGAE[j] . CGAE[k] . CGAE[l]*)