# 📐 L2 Spec — X-ray Diffraction Crystal Structure Recovery (analytical core) — Spec Skeleton
**ID:** `L2-518-001` · **Status:** ⊙ Testnet (genesis catalog)
**Parents:** ⬆ Principle [`L1-518`](/artifact/l1/L1-518)
> **🎯 Tolerance (ε):** expression
> **⚖ Difficulty score:** 0.5 · **Delta tier:** 5
> **⛓ On-chain block:** 41554145
---
## 1. Domain Ω
**Type:** `range`
| Parameter | Unit | Range |
|---|---|---|
| Snr db | dB | 10 – 50 |
| Two theta max | — | 60 – 160 |
| Two theta min | — | 1 – 30 |
| Two theta step | — | 0.001 – 0.1 |
| Beam divergence | — | [NEEDS_HAND_AUTHORING: bounds] |
| Lambda angstrom | — | 0.4 – 2.5 |
| Sample displacement | — | [NEEDS_HAND_AUTHORING: bounds] |
| Wavelength dispersion | — | [NEEDS_HAND_AUTHORING: bounds] |
| Instrumental broadening | — | 0.01 – 0.5 |
| Monochromator misalignment | — | [NEEDS_HAND_AUTHORING: bounds] |
| Background subtraction error | — | [NEEDS_HAND_AUTHORING: bounds] |
| Preferred orientation powder | — | 0.0 – 0.5 |
## 2. Tolerance (ε)
**Type:** `fn`
```
0.05_R_factor
```
## 3. Difficulty
| Property | Value |
|---|---|
| Difficulty score | 0.5 |
| Delta tier | 5 |
## 4. Fingerprint
`ff731158f957e0861cd01c87f2d8f36bad68bc41d66cbf9a60724008a9a37111`
## 5. On-chain Registration
- **Chain hash:** `0xc356d3761b4615291d3235e590c8b18f3d913e77bb69365a867935d7d79098d8`
- **Chain tx hash:** `0x50ca9f426a841746b614caa2dd18576b2ac79261dd0566297598bb3e4c144369`
- **Chain block:** `41554145`
---
## File Mapping
This bundle consists of: `L2-518-001.md`, `L2-518-001.json`.
| File | Role | How to regenerate |
|------|------|-------------------|
| `L2-518-001.md` | Source of truth — edit this | Human or LLM |
| `L2-518-001.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 `L2-518-001`._
_Edit it, regenerate the JSON, and submit at [/submit](/submit) to claim the artifact._