# 📐 L2 Spec — Focused Ion Beam SEM (FIB-SEM) — serial sectioning 3D imaging Mismatch-Only Spec
**ID:** `L2-093-001` · **Status:** ⊙ Testnet (genesis catalog)
**Parents:** ⬆ Principle [`L1-093`](/artifact/l1/L1-093)
> **🎯 Tolerance (ε):** expression
> **⚖ Difficulty score:** 0.48 · **Delta tier:** 5
> **⛓ On-chain block:** 41554188
---
## 1. Domain Ω
**Type:** `range`
| Parameter | Unit | Range |
|---|---|---|
| H | px | 512 – 4096 |
| W | px | 512 – 4096 |
| Z | — | 50 – 2000 |
| Kv | — | 1 – 5 |
| Charging | — | 0.0 – 0.3 |
| Pixel nm | nm | 1 – 50 |
| Z step nm | nm | 1 – 50 |
| Peak electrons | — | 10 – 2000 |
| Curtain artifact | — | 0.0 – 0.3 |
| Z alignment error | — | 0.0 – 2.0 |
| Milling step variance | — | 0.0 – 0.3 |
## 2. Tolerance (ε)
**Type:** `fn`
```
18.0 + 2.0 * log10(peak_electrons / 10) - 8.0 * curtain_artifact - 10.0 * milling_step_variance
```
## 3. Difficulty
| Property | Value |
|---|---|
| Difficulty score | 0.48 |
| Delta tier | 5 |
## 4. Fingerprint
`7e9fe10f32d8686b9df7f44f4db59ee0b76e3f2e3723eec809af2dbb03e2b91d`
## 5. On-chain Registration
- **Chain hash:** `0x81b1b32812ffdfe29743f8d3f7aaa979f279b7f98ecbc69b633f35694739159d`
- **Chain tx hash:** `0xb09244d775e13f8a6e3b2de086cdc054fbed185de18e1ee31a23d416f45e000d`
- **Chain block:** `41554188`
---
## File Mapping
This bundle consists of: `L2-093-001.md`, `L2-093-001.json`.
| File | Role | How to regenerate |
|------|------|-------------------|
| `L2-093-001.md` | Source of truth — edit this | Human or LLM |
| `L2-093-001.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 `L2-093-001`._
_Edit it, regenerate the JSON, and submit at [/submit](/submit) to claim the artifact._