Event Restricted Temporality (ERT): Definitions, Typing Rule, and Domain Gates — Specification v2.0

This specification defines Event‑Restricted Temporality (ERT) as a domain‑of‑applicability framework across three descriptive regimes for temporal predicates in physics. Let 𝒞 denote an admissible control set and 𝒜D an event‑license functional derived from admissible reversal cost for a description D. ERT’s core typing rule (Echo typing rule) is: temporal parameters and operators (t, ∂/∂t, time‑ordering, before/after) are admissible on D iff 𝒜D>0; structural or retentive descriptions have 𝒜D=0. A control‑relative practical threshold 𝒜* separates fragile from robust event‑license. The specification provides domain gates (“Eight Doors”), diagnostic failure modes, worked robustness examples, and the reverse‑priority interpretive rule (Event ⊣ Time ⊣ Evolution). Appendix A includes an optional ℰ label (as used in the companion domain‑gates formulation) for the event‑restriction schematic. A recommended citation string and change log are included for stable reference. This document is intended as a citable definitional specification (reference standard-canonical definitional specification of the Event‑Restricted Temporality (ERT) framework.), not a research article.