# ADR-0005: Multi-Layer Settlement Architecture

## Status
Accepted

## Context
The DBIS system requires settlement across multiple dimensions:
- Multiple sovereign banks (33 SCBs)
- Multiple asset types (fiat, CBDC, commodities, securities)
- Multiple settlement modes (RTGS, atomic, T+1)
- Cross-chain operations
- Real-time and batch processing

## Decision
Implement a multi-layer settlement architecture:
1. **Instant Settlement Network (ISN)**: Real-time atomic settlement
2. **Global Settlement System (GSS)**: Four-layer architecture (Sovereign, DBIS Master, Smart Clearing, Finality)
3. **Global Atomic Settlements (GAS) Network**: Multi-dimensional atomic settlement
4. **Omega-Layer**: Final settlement layer for reality-spanning coherence
5. **Cross-Chain Settlement**: Atomic swaps across different chains

## Consequences

### Positive
- Supports multiple settlement modes
- Atomic settlement guarantees
- Cross-asset settlement capability
- Scalable architecture
- Finality and irreversibility

### Negative
- Complex architecture
- Multiple systems to maintain
- Potential for coordination overhead

### Risks
- Settlement failures across layers
- Performance at scale
- Complexity in debugging

## Alternatives Considered

1. **Single Settlement Layer**: One settlement system
   - Pros: Simple
   - Cons: Cannot handle all requirements

2. **Multi-Layer Architecture**: Chosen approach
   - Pros: Flexible, comprehensive, supports all use cases
   - Cons: More complex

## Implementation
- ISN: `src/core/settlement/isn/`
- GSS: `src/core/settlement/gss/`
- GAS: `src/core/settlement/gas/`
- Cross-Chain: `src/core/settlement/cross-chain/`

## References
- ISO 20022 Settlement Standards
- Real-Time Gross Settlement (RTGS) Systems