Remark: Optional collar module

An independently installed collar refinement can split every resting $Q_i$ by $\rho =u$, $7/2<u<4$, while holding a regular $s$ and $\mu$ fixed. Its chord length is $u{L}_{\vartheta }$; its two ray pieces have lengths $u-r$ and $4-u$. Changing $u$ changes those subdivision lengths but not the embedded horizontal slice. All new overlaps have identity ambient transition, so the peripheral certificate is unchanged. This module is not inserted silently during a source or incidence command.