# 📐 L2 Spec — Underwater Acoustic Ray Tracing (Bellhop) Mismatch-Only Spec
**ID:** `L2-262-001` · **Status:** ⊙ Testnet (genesis catalog)
**Parents:** ⬆ Principle [`L1-262`](/artifact/l1/L1-262)
> **🎯 Tolerance (ε):** expression
> **⚖ Difficulty score:** 0.48 · **Delta tier:** 5
> **⛓ On-chain block:** 41554052
---
## 1. Domain Ω
**Type:** `range`
| Parameter | Unit | Range |
|---|---|---|
| N rays | — | 1000 – 1000000 |
| Snr db | dB | -10 – 40 |
| N depth | — | 32 – 1024 |
| N range | — | 64 – 4096 |
| Freq hz | Hz | 10 – 100000 |
| Ssp error | — | 0.0 – 0.02 |
| Range error | — | 0.0 – 50.0 |
| Bathymetry error | — | 0.0 – 10.0 |
| Bottom properties error | — | 0.0 – 0.3 |
## 2. Tolerance (ε)
**Type:** `fn`
```
2.0 + 20.0*ssp_error + 0.2*bathymetry_error + 8.0*bottom_properties_error - 0.03*SNR_dB
```
## 3. Difficulty
| Property | Value |
|---|---|
| Difficulty score | 0.48 |
| Delta tier | 5 |
## 4. Fingerprint
`89ab9a42b9929dfa4e2f96e7b8bd70bcaf253e465eeda509b3d9423e83c9e158`
## 5. On-chain Registration
- **Chain hash:** `0xc31126ef603c51df2c2e5ed889d740e2f9be2470c69a9cdc4eab8066e95516c0`
- **Chain tx hash:** `0xa9fe37a61e2eeab0ed9b68a2c838482d8648c59e43c6d47c719aaf4777879309`
- **Chain block:** `41554052`
---
## File Mapping
This bundle consists of: `L2-262-001.md`, `L2-262-001.json`.
| File | Role | How to regenerate |
|------|------|-------------------|
| `L2-262-001.md` | Source of truth — edit this | Human or LLM |
| `L2-262-001.json` | Structured metadata for the registry | LLM regenerates from the sections above |
**Prompt for your LLM after editing this Markdown:**
> Read the attached Markdown. Regenerate the sibling `.json` so every field matches.
> Preserve the schema documented in the rows above.
> Output each file in its own fenced code block tagged with the filename.
> Output only the JSON object.
_This Markdown was auto-synthesized from the catalog row for `L2-262-001`._
_Edit it, regenerate the JSON, and submit at [/submit](/submit) to claim the artifact._