The inherited characteristic configuration

Figure fig:xiii-e-null-line is the selected configuration. It is not a cancellation theorem.

XIII-C supplies a nonzero line-covector selection whose sums vanish at all three vertices. This incidence occurs in the selected pair. It does not prove that summing the complete tensor coefficients cannot cancel a singular contribution.

The present attempt retains those coefficients. It neither deletes the incidence nor adds a subtraction supported on a noncoincident null locus.