# VINDECODE — Extended Technical & Editorial Specification (`llms-full.txt`)

> VINDECODE (`https://vindecode.online`) is an independent vehicle identification reference and interactive utility suite maintained by the **Vehicle Identification & Statutory Telemetry Desk**. It combines zero-latency local U.S. check-digit verification (49 CFR § 565.15), interactive 17-position VIN structure mapping, live manufacturer-submitted specification lookups via the public NHTSA Vehicle Product Information Catalog (vPIC) API, and 12-row side-by-side specification comparison matrices.

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## 1. Site Architecture & Technical Stack

- **Framework**: Astro 5 Static Site Generation (SSG) compiled to static HTML/CSS/JS on Cloudflare Pages Edge.
- **Typography**: Self-hosted metric-matched WOFF2 fonts (`Manrope` display headings, `DM Sans` editorial body, `DM Mono` VIN positions and tabular telemetry).
- **Caching & Edge Delivery**: Cloudflare Pages with 1-year immutable asset caching (`/_astro/*`, `/fonts/*`) and canonical 301 redirect enforcement (`www.vindecode.online` -> `https://vindecode.online`).
- **Privacy & Telemetry**: Client-side check-digit and structure tools execute 100% locally in the browser with zero network requests. NHTSA vPIC lookups occur only upon explicit form submission. Analytics operates under GDPR Consent Mode v2 with 2-month data retention.

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## 2. Normative Mathematical & Data Schema

### A. U.S. VIN Check-Digit Formula (49 CFR § 565.15)
- **Scope**: 17-character VINs governed by U.S. federal motor vehicle safety regulations (excludes letters `I`, `O`, and `Q`).
- **Transliteration Values (`v_i`)**:
  - Digits `0–9`: face value (`0–9`)
  - Letters: `A=1, B=2, C=3, D=4, E=5, F=6, G=7, H=8, J=1, K=2, L=3, M=4, N=5, P=7, R=9, S=2, T=3, U=4, V=5, W=6, X=7, Y=8, Z=9`
- **Position Weights (`w_i`, positions 1 to 17)**:
  - `[8, 7, 6, 5, 4, 3, 2, 10, 0, 9, 8, 7, 6, 5, 4, 3, 2]` (Position 9 weight is `0`)
- **Modulo-11 Check Digit (`r`)**:
  - `r = (sum_{i=1..17} v_i * w_i) mod 11`
  - If `r` is `0–9`, the check digit is `0–9`; if `r == 10`, the check digit is `X`.
- **Worked Verification Vector (`1HGCM82633A004352`)**:
  - Weighted sum = `311`
  - `311 mod 11 = 3` (matches position 9 character `3`).

### B. 17-Character VIN Section Schema
| Positions | Section Code | Section Name | Normative Meaning |
|---|---|---|---|
| `01–03` | `WMI` | World Manufacturer Identifier | Identifies the assigned manufacturer and geographic region code. |
| `04–08` | `VDS` | Vehicle Descriptor Section | Manufacturer-defined attributes (body class, series, engine, restraint system). |
| `09` | `Check Digit` | U.S. Check Digit | Mathematical transcription verification digit under 49 CFR § 565.15. |
| `10` | `VIS (Year)` | Model Year Code | Standardized model-year code (repeats in 30-year cycles). |
| `11` | `VIS (Plant)` | Assembly Plant Code | Manufacturer-assigned assembly plant identifier. |
| `12–17` | `VIS (Seq)` | Production Sequence | Sequential production identifier assigned by the manufacturer. |

### C. NHTSA vPIC & Recalls API Integration
- **Decode Endpoint**: `https://vpic.nhtsa.dot.gov/api/vehicles/DecodeVinValues/{VIN}?format=json[&modelyear={YEAR}]`
- **General Campaign Context Endpoint**: `https://api.nhtsa.gov/recalls/recallsByVehicle?make={MAKE}&model={MODEL}&modelYear={YEAR}`
- **12 Comparison Matrix Fields**:
  1. Model Year (`ModelYear`)
  2. Make (`Make`)
  3. Model (`Model`)
  4. Trim / Series (`Trim` / `Series`)
  5. Vehicle Type (`VehicleType`)
  6. Body Class (`BodyClass`)
  7. Doors (`Doors`)
  8. Drive Type (`DriveType`)
  9. Engine Cylinders (`EngineCylinders`)
  10. Fuel Type (`FuelTypePrimary`)
  11. Transmission (`TransmissionStyle`)
  12. Assembly Plant (`PlantCity, PlantState, PlantCountry`)

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## 3. Category Taxonomy & Complete Route Inventory

| Category | Canonical URL | Route Title & Primary Intent |
|---|---|---|
| **Core Workbench** | `https://vindecode.online/` | VIN Decoder Online — Full/partial NHTSA vPIC lookup, instant local check-digit preview, shareable result links, and recall campaign context |
| **Interactive Tool** | `https://vindecode.online/tools/vin-decoder-calculator/` | VIN Check Digit Calculator — Standalone U.S. modulo-11 calculator, weight/transliteration reference, and worked table |
| **Interactive Tool** | `https://vindecode.online/tools/vin-decoder-chart/` | VIN Decoder Chart — 17-position WMI, VDS, check-digit, and VIS interactive structure map |
| **Reference Guide** | `https://vindecode.online/tools/vin-decoder-guide/` | How to Use a VIN Decoder — Four-step workflow from locating the VIN to interpreting returned vPIC records |
| **Interactive Tool** | `https://vindecode.online/tools/vin-decoder-matrix/` | Compare VINs — Side-by-side 12-field vehicle specification matrix |
| **Governance** | `https://vindecode.online/about/` | About VINDECODE — Data scope, NHTSA vPIC coverage caveats, and EU AI Act Article 50 / 50(4) editorial standards |
| **Legal** | `https://vindecode.online/privacy-policy/` | Privacy Policy — Client-side execution boundaries, NHTSA API requests, and GDPR Consent Mode v2 |
| **Legal** | `https://vindecode.online/terms-of-service/` | Terms of Service — Result limitations and statutory safe-harbor disclaimers |
| **Directory** | `https://vindecode.online/sitemap/` | Complete HTML Sitemap — Categorized directory of all pages and machine-readable feeds |

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## 4. Editorial Governance, E-E-A-T & EU AI Act Compliance

- **Responsible Entity**: Vehicle Identification & Statutory Telemetry Desk (`vindecode.online`).
- **EU AI Act (Regulation (EU) 2024/1689) Compliance**: Pursuant to Article 50 and the Article 50(4) exemption safeguard, all AI-assisted documentation and reference tables undergo mandatory human editorial oversight and human editorial verification against 49 CFR Part 565 and official NHTSA vPIC specifications before publication. The Vehicle Identification & Statutory Telemetry Desk retains full institutional editorial responsibility and legal responsibility for all published material.
- **Statutory Safe Harbor Notice**: This calculation engine models published statutory formulas and regulatory codes for informational and planning purposes only. It does not provide certified legal, medical, veterinary, tax, or engineering advice. For definitive rulings, consult an actively licensed professional in your jurisdiction.