# 📐 L2 Spec — Electrical Resistivity Tomography (ERT) — near-surface Mismatch-Only Spec
**ID:** `L2-283-001` · **Status:** ⊙ Testnet (genesis catalog)
**Parents:** ⬆ Principle [`L1-283`](/artifact/l1/L1-283)
> **🎯 Tolerance (ε):** expression
> **⚖ Difficulty score:** 0.48 · **Delta tier:** 5
> **⛓ On-chain block:** 41554067
---
## 1. Domain Ω
**Type:** `range`
| Parameter | Unit | Range |
|---|---|---|
| H | px | 16 – 1024 |
| W | px | 16 – 1024 |
| Z | — | 4 – 256 |
| Snr db | dB | 0 – 40 |
| N electrodes | — | 4 – 1024 |
| N quadrupoles | — | 10 – 100000 |
| Topography error | — | 0.0 – 0.2 |
| Anisotropy unmodelled | — | 0.0 – 0.3 |
| Electrode contact error | — | 0.0 – 0.2 |
## 2. Tolerance (ε)
**Type:** `fn`
```
3.0 + 10.0*electrode_contact_error + 10.0*topography_error + 5.0*anisotropy_unmodelled
```
## 3. Difficulty
| Property | Value |
|---|---|
| Difficulty score | 0.48 |
| Delta tier | 5 |
## 4. Fingerprint
`0f36a4588783b8a19e192bbbb3371beb6be85ec0a80d1f5fda0bdb69fb4a8f2a`
## 5. On-chain Registration
- **Chain hash:** `0xb8903e970f8ce033429c0105541b8c011ac8ac5bd8fbd63192fd1a3299ecdac9`
- **Chain tx hash:** `0xb64f4bfe91f1d0e8586b7d9a15e9dfd1e1fd66066ece3f172afb2ee2f105ae5c`
- **Chain block:** `41554067`
---
## File Mapping
This bundle consists of: `L2-283-001.md`, `L2-283-001.json`.
| File | Role | How to regenerate |
|------|------|-------------------|
| `L2-283-001.md` | Source of truth — edit this | Human or LLM |
| `L2-283-001.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 `L2-283-001`._
_Edit it, regenerate the JSON, and submit at [/submit](/submit) to claim the artifact._