Add data classification standard

standards/data-classification.md

@@ -0,0 +1,18 @@
+# Data Classification Standard
+
+**Version:** 1.0  |  **Owner:** Compliance  |  **Classification:** Internal
+
+## Classification levels
+
+| Level | Examples | Handling |
+|-------|---------|---------|
+| Public | Marketing materials, press releases | No restrictions |
+| Internal | This document, org charts | Nexus staff only |
+| Confidential | Customer data, financial reports | Need-to-know, encrypt at rest |
+| Restricted | Credentials, encryption keys, PII | Vault only, no email, audit logged |
+
+## PII handling
+
+All personally identifiable information is classified as **Confidential** minimum.
+Processing of PII requires GDPR lawful basis and must be documented in the data register.
+Contact dpo@nexus.local with questions.