Remark: Correction to the brief

The brief writes ${{\Phi }^{(2)}}_{\mathrm{D}}={{\mathcal{A}}_2}^{\mathrm{sc}}+{\mathcal{C}}_{3,\mathrm{D}}$. Proposition prop:single replaces the sign. The replacement is not a convention: XII-D's $u_{\mathrm{D}}$ solves $Lu={\mathcal{J}}_{\mathrm{D}}$, the metric coefficient solves $Lr=-{\mathcal{J}}_{\mathrm{D}}$, and the affine identity is linear. The “$+$” version is named ${{\Phi }^{(2)}}_{+}$ in Proposition prop:signdetect and shown to carry a defect that no plateau hypothesis removes.