What changes at the event

The construction is a three-to-six particle-link expansion. For negative parameters, three sloping faces meet at the particle. For positive parameters, six different sloping faces meet there. The old three faces remain in the cellulation, but cease to be incident to the particle.

This is one isolated event in the prescribed one-parameter family. It is a simultaneous local expansion, not a claim of genericity in the space of all slicings and not an identification with one particular elementary transition from a classical catalogue.