# GS1 Verification Router Service (VRS) Lightweight Messaging Spec
> GS1 Verification Router Service (VRS) protocol engine for automated saleable drug returns verification in under 5ms.

- **Canonical URL:** https://stanzaapi.com/tools/pharma-dscsa/compliance/vrs-verification-router-service
- **Governing Standard:** 21 U.S. Code § 360eee / GS1 EPCIS (U.S. Food & Drug Administration (FDA) DSCSA)
- **Latency:** <3ms Edge
- **Privacy:** In-memory execution only (zero data stored or logged)

## Technical Overview & Governing Rules
Under DSCSA Section 582, wholesale distributors must verify the product identifier (GTIN, SN, Lot, Exp) with the manufacturer prior to redistributing returned drug packages.

The GS1 Lightweight Messaging Standard for VRS defines standard RESTful JSON request and response payloads exchanged via secure routing lookups.

## Specification Matrix
| JSON Attribute | Type | Description | Validation Rule |
| --- | --- | --- | --- |
| gtin | String (14 digits) | Global Trade Item Number | Valid Modulo-10 checksum |
| serialNumber | String (1-20 chars) | Unique Serial Identifier | Alphanumeric regex: ^[A-Za-z0-9-._]{1,20}$ |
| expirationDate | String (YYMMDD / ISO) | Product Expiration Date | Valid date format |
| lotNumber | String (1-20 chars) | Manufacturing Batch Code | Alphanumeric identifier |

## Standard JSON Response Model
```json
{
  "vrsRequest": {
    "gtin": "00301234567896",
    "serialNumber": "123456789012",
    "expirationDate": "260831",
    "lotNumber": "LOT99881"
  },
  "vrsResponse": {
    "verificationResult": "SUCCESS",
    "verified": true,
    "timestamp": "2026-08-30T12:00:00Z"
  }
}
```

## Frequently Asked Questions & Edge Cases
### Q: What is the required response time for a DSCSA VRS verification request?
**A:** Industry standards mandate sub-second response times, and our edge-based engine resolves verification parsing in <5ms.