# 📐 L2 Spec — Phased-Array Ultrasonic Testing (PAUT) Mismatch-Only Spec
**ID:** `L2-113-001` · **Status:** ⊙ Testnet (genesis catalog)
**Parents:** ⬆ Principle [`L1-113`](/artifact/l1/L1-113)
> **🎯 Tolerance (ε):** expression
> **⚖ Difficulty score:** 0.5 · **Delta tier:** 5
> **⛓ On-chain block:** 41554202
---
## 1. Domain Ω
**Type:** `range`
| Parameter | Unit | Range |
|---|---|---|
| F mhz | MHz | 0.5 – 25 |
| Snr db | dB | 0.0 – 30.0 |
| N angles | — | 11 – 181 |
| Range mm | mm | 5 – 500 |
| N elements | — | 16 – 256 |
| Grain noise | — | 0.0 – 0.3 |
| Wedge coupling | — | 0.3 – 1.0 |
| Surface curvature | — | 0.0 – 0.5 |
| Sound speed uncertainty | — | 0.0 – 0.05 |
## 2. Tolerance (ε)
**Type:** `fn`
```
16.0 + 0.3 * SNR_dB + 8.0 * wedge_coupling - 10.0 * surface_curvature - 20.0 * sound_speed_uncertainty
```
## 3. Difficulty
| Property | Value |
|---|---|
| Difficulty score | 0.5 |
| Delta tier | 5 |
## 4. Fingerprint
`fc436d4fd38b195a6ceb1f049a6e84dbedb59406374b993bfd3bfb3fb6516d7f`
## 5. On-chain Registration
- **Chain hash:** `0x90747613c8771bb6dafde8bcc3b4ac2bb54cc0b4c783c03bb21db40f11fe46c2`
- **Chain tx hash:** `0xde5e090344e7d983f9dc4210255b55559e63643d2c32c9998a35d84305f56e4c`
- **Chain block:** `41554202`
---
## File Mapping
This bundle consists of: `L2-113-001.md`, `L2-113-001.json`.
| File | Role | How to regenerate |
|------|------|-------------------|
| `L2-113-001.md` | Source of truth — edit this | Human or LLM |
| `L2-113-001.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 `L2-113-001`._
_Edit it, regenerate the JSON, and submit at [/submit](/submit) to claim the artifact._