# 📐 L2 Spec — Photonic Inverse Design — nanostructure topology optimization Mismatch-Only Spec
**ID:** `L2-248-001` · **Status:** ⊙ Testnet (genesis catalog)
**Parents:** ⬆ Principle [`L1-248`](/artifact/l1/L1-248)
> **🎯 Tolerance (ε):** expression
> **⚖ Difficulty score:** 0.48 · **Delta tier:** 5
> **⛓ On-chain block:** 41553993
---
## 1. Domain Ω
**Type:** `range`
| Parameter | Unit | Range |
|---|---|---|
| H | px | 32 – 2048 |
| W | px | 32 – 2048 |
| N iter | — | 10 – 100000 |
| Snr db | dB | 10 – 60 |
| N freqs | — | 1 – 256 |
| Source error | — | 0.0 – 0.1 |
| Material error | — | 0.0 – 0.1 |
| Fab discretization error | — | 0.0 – 0.2 |
## 2. Tolerance (ε)
**Type:** `fn`
```
0.7 + 0.005*SNR_dB - 0.5*fab_discretization_error - 0.4*material_error - 0.3*source_error
```
## 3. Difficulty
| Property | Value |
|---|---|
| Difficulty score | 0.48 |
| Delta tier | 5 |
## 4. Fingerprint
`cec0d3c29503a0f36a219846ea4a5eba36ae2a202d028931f9251b9dcfd48af2`
## 5. On-chain Registration
- **Chain hash:** `0x4bb3e4b84109f57eb60d8ebb417f84b40439b0f2554044d58f4822ff1d326e1c`
- **Chain tx hash:** `0x33ea2f73db611abb5afd4afa19e0a3b63a7866813442257c7b255b40377e00a6`
- **Chain block:** `41553993`
---
## File Mapping
This bundle consists of: `L2-248-001.md`, `L2-248-001.json`.
| File | Role | How to regenerate |
|------|------|-------------------|
| `L2-248-001.md` | Source of truth — edit this | Human or LLM |
| `L2-248-001.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 `L2-248-001`._
_Edit it, regenerate the JSON, and submit at [/submit](/submit) to claim the artifact._