Data Spec Index

This folder defines what is stored, where, and in what format for the offline NFC wallet system. It is the authoritative source for field definitions, binary layouts, backend schema, encoding rules, and versioning contracts.

Data Spec is Layer 5. It depends on Tech Specs (Layer 3) for behaviour rules and System Design (Layer 2) for the conceptual model. API Spec (Layer 4) depends on this layer for payload field definitions.

Sections

1. Overview — storage areas, ownership, and data flow
2. Card Binary Schema — full binary layout for NFC card payload
3. Backend DB Schema — server-side entities and SQL DDL
4. Encoding Conventions & Versioning — endianness, encoding rules, schema versions, migrations

Upstream sources

• System Design §5: Data Layout
• Tech Specs §3: Card Storage Model
• Tech Specs §14: Transaction Log Format
• Tech Specs §15: Status Codes & Block Rules

Downstream layers

• API Spec: docs/api-spec/
• Security Spec: docs/security-spec/ (not yet written)
• Test Spec: docs/test-spec/ (not yet written)