# External source check (ECOM-MARGIN-20260831)

Checked 2026-09-04 with `scripts/verify-external-sources.py` (GET, follow redirects, 25s timeout). None of these pages audited this fixture. Machine log: [`external-source-check-ECOM-MARGIN-20260831.json`](./external-source-check-ECOM-MARGIN-20260831.json).

| Source | Requested URL | Final URL | HTTP | Title SHA-256 | Note | Use |
|---|---|---|---|---|---|---|
| Quarterly Retail E-Commerce Sales | https://www.census.gov/retail/ecommerce.html | https://www.census.gov/retail/ecommerce.html | 200 | 67d22742012e1e63 |  | Official aggregate market context |
| Mail, Internet, or Telephone Order Merchandise Rule | https://www.ftc.gov/legal-library/browse/rules/mail-internet-or-telephone-order-merchandise-rule | https://www.ftc.gov/legal-library/browse/rules/mail-internet-or-telephone-order-merchandise-rule | 200 | 029f7e83bd53df09 |  | Order-fulfillment regulatory context |
| Assessing Data Reliability | https://www.gao.gov/products/gao-20-283g | https://www.gao.gov/products/gao-20-283g | 200 | 4b63162eff92e4ec |  | Data-reliability assessment principles |
| RFC 4180 | https://www.rfc-editor.org/rfc/rfc4180 | https://www.rfc-editor.org/info/rfc4180/ | 200 | 724d7aa6f8ad4c5b |  | CSV format context |
| Ecommerce analytics | https://www.shopify.com/enterprise/blog/ecommerce-analytics | https://www.shopify.com/enterprise/blog/google-analytics-ecommerce-tracking | 200 | 4696cf6a56dc0cc3 |  | Vendor-authored metric context |

Keep original requested URLs. Re-check at decision time.