Empirical Dark-Matter Relaxation Observable (η): Canonical Definition, Ontology, and Data Release (v1.2)

This record defines and preserves a canonical empirical relaxation observable for disk galaxies. The primary observable is the dimensionless relaxation parameter η, defined as the ratio between the observed inner circular velocity and a collisionless reference prediction evaluated at a fixed physical radius of r₀ = 2.5 kpc: η = V_obs(2.5 kpc) / V_CDM(2.5 kpc) η is strictly empirical, model-agnostic, and simulation-independent. It functions as an ordering or state parameter for inner galaxy dynamics and does not assume any dark-matter microphysics. η is not a scattering rate, cross section, potential, or particle-physics parameter. A derived framework coordinate R is included for cataloging and visualization purposes only. R has no independent physical meaning, and all physical interpretation traces back exclusively to η. This release provides:- formal, machine-readable definitions of all observables- a single canonical analysis-ready dataset- a fully reproducible reference pipeline with uncertainty propagation- cryptographic hashes for long-term integrity verification This record defines the observable itself.Supporting analyses and narrative papers demonstrate and explore the observable but do not redefine it. Citation:“as defined in Riolo (2026)”