Proposition: Regular separated-cone orders and amplitudes

Each placement of $K_5$ has a conormal representation of upper order one on its corresponding separated two-cone relation.

The normal amplitude is the finite polynomial obtained by differentiating

and multiplying by the full coefficients in (eq:K5). This statement includes all lower differential terms on these regular charts.

Proof. On these sectors both retarded time factors are constant one. The two defining functions are regular and independent. The undifferentiated normal amplitude has degree zero, and the displayed kernel has at most four derivatives.

The ambient dimension is sixteen and the regular base codimension is two. Equation (eq:order) gives

The exact polynomial amplitude description follows by applying the finite differential expression to the two normal deltas.