Proposition: Contact changes and strict ordering

A well-defined contact change in ${\mathfrak{C}}_{\mathrm{part}}$ involving an interaction and an observable attachment cannot alter a region in which the full functional supports are strictly ordered and disjoint. The constructed primitive contacts therefore preserve the off-collision ordered values on their domains.

Proof. Strict separation prohibits equality of any interaction attachment with an observable attachment. Every relevant contact is supported on a collision containing such an equality. Its restriction to the strictly separated region is zero.