End CfDotOrthonormal.

Lemma zchar_small_norm phi n :
phi \in 'Z[irr G] -> '[phi] = n%:R -> (n < 4)%N ->
{S : n.-tuple 'CF(G) |
[/\ orthonormal S, {subset S <= 'Z[irr G]} & phi = \sum_(xi <- S) xi]}.