Cosmological Redshift as Kinematic Scale Labeling: An Operational Clarification on Wavelength Assignment and the Limits of Mechanism Language

This preprint examines the operational content of the standard cosmological redshift relation. It argues that the identity 1 + z = λ_obs / λ_emit does not by itself determine an underlying physical mechanism, and it clarifies the distinction between kinematic bookkeeping and dynamical interpretation. Under a minimal wavelength-assignment rule with a monotonically ordered scale label, the standard relation 1 + z = a_obs / a_emit follows algebraically. The manuscript does not propose a new cosmology, does not derive an independent epoch tag, and does not discriminate among cosmological models sharing the same kinematic form. It is shared as a public preprint and has not been peer reviewed.