# 📐 L2 Spec — Joint MEG-EEG Source Imaging — Spec Skeleton
**ID:** `L2-507-001` · **Status:** ⊙ Testnet (genesis catalog)
**Parents:** ⬆ Principle [`L1-507`](/artifact/l1/L1-507)
> **🎯 Tolerance (ε):** expression
> **⚖ Difficulty score:** 0.5 · **Delta tier:** 5
> **⛓ On-chain block:** 41553362
---
## 1. Domain Ω
**Type:** `range`
| Parameter | Unit | Range |
|---|---|---|
| Snr db | dB | 0.0 – 35.0 |
| N dipoles | — | 1000 – 30000 |
| T samples | — | 100 – 100000 |
| N eeg channels | — | 0 – 256 |
| N meg channels | — | 0 – 306 |
| Head layer count | — | 3 – 7 |
| Sampling rate hz | Hz | 256 – 5000 |
| Sensor position error | — | 0.0 – 0.2 |
| Head segmentation error | — | 0.0 – 0.3 |
| Conductivity uncertainty | — | 0.0 – 0.5 |
| Reference electrode drift | — | 0.0 – 0.3 |
| Source orientation assumption | — | [NEEDS_HAND_AUTHORING: bounds] |
| Magnetic artifact contamination | — | 0.0 – 0.4 |
## 2. Tolerance (ε)
**Type:** `fn`
```
20.0
```
## 3. Difficulty
| Property | Value |
|---|---|
| Difficulty score | 0.5 |
| Delta tier | 5 |
## 4. Fingerprint
`eeb0d48342afad40ac6cb59e4177560ce52ebfeb38bd1af2822d94f3713d7f06`
## 5. On-chain Registration
- **Chain hash:** `0x50c593be59225c373fd8ba364656f371df511ff8e6c57ea7f80e8ee829aeaa40`
- **Chain tx hash:** `0x9f63f939c0988147d93ef168f4c8cbd0f35fa7023a86f2a9639314d27e9140a4`
- **Chain block:** `41553362`
---
## File Mapping
This bundle consists of: `L2-507-001.md`, `L2-507-001.json`.
| File | Role | How to regenerate |
|------|------|-------------------|
| `L2-507-001.md` | Source of truth — edit this | Human or LLM |
| `L2-507-001.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 `L2-507-001`._
_Edit it, regenerate the JSON, and submit at [/submit](/submit) to claim the artifact._