Structural Rating Tiers
R1 / R3 / R5
R1, R3, and R5 are BCI's three public classification bands for structural integrity, on a 0.0–10.0 composite scale, with two internal-only transitional monitoring bands between them.
| Tier | Name | Range | External |
|---|---|---|---|
R1 | Structural Integrity | > 8.5 | Yes |
R2 | Transitional Monitoring Band | ≈ 8.0–8.5 | No |
R3 | Structural Fatigue | ≈ 6.5–8.0 | Yes |
R4 | Transitional Monitoring Band | ≈ 6.0–6.5 | No |
R5 | Systemic Breakdown | < 6.0 | Yes |
These boundary values are current working assumptions, not values derived from a completed distribution of real composite readings. As of this writing, zero cases in the internal backtest registry have all four variables (MT, PL, TS, ES) independently computed from real data. The planned method — outcome separation across completed cases, not a fixed percentile cut — is set out in BSIP v4.0 §9.2.
Relationship to the Public Protocol Annex
R1/R3/R5 are the universal, cross-sector labels. The Public Protocol Annex publishes a sector-specific numeric implementation of this same tier system for luxury hard assets (9.0+ / 8.5–8.9 / 8.0–8.4 / 7.5–7.9 / <7.5) — set higher because that population skews structurally high. Other sectors require their own sector-specific tables before their scores can be read against a sector-calibrated line.