# 📐 L2 Spec — Linear Elastic Fracture Mechanics (LEFM) — K/J evaluation Mismatch-Only Spec
**ID:** `L2-220-001` · **Status:** ⊙ Testnet (genesis catalog)
**Parents:** ⬆ Principle [`L1-220`](/artifact/l1/L1-220)
> **🎯 Tolerance (ε):** expression
> **⚖ Difficulty score:** 0.48 · **Delta tier:** 5
> **⛓ On-chain block:** 41554015
---
## 1. Domain Ω
**Type:** `range`
| Parameter | Unit | Range |
|---|---|---|
| N dof | — | 1000 – 10000000 |
| Snr db | dB | 0 – 40 |
| N contours | — | 1 – 50 |
| Material error | — | 0.0 – 0.1 |
| Contour size error | — | 0.0 – 0.3 |
| Crack tip pos error | — | 0.0 – 0.1 |
## 2. Tolerance (ε)
**Type:** `fn`
```
2.0 + 20.0*crack_tip_pos_error + 8.0*contour_size_error + 20.0*material_error
```
## 3. Difficulty
| Property | Value |
|---|---|
| Difficulty score | 0.48 |
| Delta tier | 5 |
## 4. Fingerprint
`e605b7827b611e5af9c73a96ab42b8244ba235d8529a825025736b096483a4e5`
## 5. On-chain Registration
- **Chain hash:** `0x384fd02d7e8ab0356f307de7babd6fb5426e303a771e912d1e94220f24e6456a`
- **Chain tx hash:** `0x38e51c8ec96a4b12c21e83b1fa2d187c3e432b93da83f508c94a113edca696d9`
- **Chain block:** `41554015`
---
## File Mapping
This bundle consists of: `L2-220-001.md`, `L2-220-001.json`.
| File | Role | How to regenerate |
|------|------|-------------------|
| `L2-220-001.md` | Source of truth — edit this | Human or LLM |
| `L2-220-001.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 `L2-220-001`._
_Edit it, regenerate the JSON, and submit at [/submit](/submit) to claim the artifact._