# 📐 L2 Spec — Quantitative Susceptibility Mapping (QSM) — Spec Skeleton
**ID:** `L2-503-001` · **Status:** ⊙ Testnet (genesis catalog)
**Parents:** ⬆ Principle [`L1-503`](/artifact/l1/L1-503)
> **🎯 Tolerance (ε):** expression
> **⚖ Difficulty score:** 0.5 · **Delta tier:** 5
> **⛓ On-chain block:** 41553362
---
## 1. Domain Ω
**Type:** `range`
| Parameter | Unit | Range |
|---|---|---|
| H | px | 128 – 512 |
| W | px | 128 – 512 |
| Z | — | 32 – 256 |
| Snr db | dB | 10.0 – 40.0 |
| N echoes | — | 1 – 12 |
| Te ms max | — | 10.0 – 80.0 |
| Te ms min | — | 2.0 – 15.0 |
| B0 field t | — | 1.5 – 7.0 |
| Voxel size mm | mm | 0.5 – 2.0 |
| B0 inhomogeneity | — | 0.0 – 0.3 |
| Phase unwrap error | — | 0.0 – 0.3 |
| Brain segmentation error | — | 0.0 – 0.2 |
| Background field removal error | — | 0.0 – 0.3 |
| Dipole kernel truncation error | — | 0.0 – 0.2 |
## 2. Tolerance (ε)
**Type:** `fn`
```
30.0
```
## 3. Difficulty
| Property | Value |
|---|---|
| Difficulty score | 0.5 |
| Delta tier | 5 |
## 4. Fingerprint
`fa7c8f90f8a42ae7331c52030949110c85c3cccf14fd108e8efc138ff37a4ced`
## 5. On-chain Registration
- **Chain hash:** `0x0d678310e66b8f72d895851fb78461fec300001e9a01d00d82e99db4a1f721d5`
- **Chain tx hash:** `0x99c0c961ba8ec6721418205dec38b30f557b417248f26a13f524c91168d1ecf0`
- **Chain block:** `41553362`
---
## File Mapping
This bundle consists of: `L2-503-001.md`, `L2-503-001.json`.
| File | Role | How to regenerate |
|------|------|-------------------|
| `L2-503-001.md` | Source of truth — edit this | Human or LLM |
| `L2-503-001.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 `L2-503-001`._
_Edit it, regenerate the JSON, and submit at [/submit](/submit) to claim the artifact._