# 📐 L2 Spec — EXAFS Radial-Fit Spec
**ID:** `L2-147-001` · **Status:** ⊙ Testnet (genesis catalog)
**Parents:** ⬆ Principle [`L1-147`](/artifact/l1/L1-147)
> **🎯 Tolerance (ε):** expression
> **⚖ Difficulty score:** 0.58 · **Delta tier:** 5
> **⛓ On-chain block:** 41554231
---
## 1. Domain Ω
**Type:** `range`
| Parameter | Unit | Range |
|---|---|---|
| N e | — | 50 – 2000 |
| K max | — | 4 – 16 |
| Snr db | dB | -5 – 45 |
| K shells | — | 1 – 10 |
| S 0 squared | — | 0.5 – 1.0 |
| E0 shift ev | — | -5 – 5 |
| Detector saturation | — | 0.0 – 0.2 |
| Self absorption correction | — | 0.0 – 0.3 |
| Multiple scattering truncation | — | 1 – 5 |
## 2. Tolerance (ε)
**Type:** `fn`
```
0.005 + 0.01 * abs(e0_shift_eV) + 0.05 * (1 - S_0_squared) + 0.02 * self_absorption_correction
```
## 3. Difficulty
| Property | Value |
|---|---|
| Difficulty score | 0.58 |
| Delta tier | 5 |
## 4. Fingerprint
`a04cbf33efc98a468f9a9b2a88ccf47040d80575418cb9c9986b84c7c1b524db`
## 5. On-chain Registration
- **Chain hash:** `0xfa220fe56012161e9c38916145591e0507f2a18a46cda5b3c54ec9a64bc0fb38`
- **Chain tx hash:** `0x0f8f3173e07c91c18e73e0f14351d0fb84b8db00da970b00f1929667d4bb63ab`
- **Chain block:** `41554231`
---
## File Mapping
This bundle consists of: `L2-147-001.md`, `L2-147-001.json`.
| File | Role | How to regenerate |
|------|------|-------------------|
| `L2-147-001.md` | Source of truth — edit this | Human or LLM |
| `L2-147-001.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 `L2-147-001`._
_Edit it, regenerate the JSON, and submit at [/submit](/submit) to claim the artifact._