May 24, 2026
Design documents describe how requirements will be implemented. They bridge requirements → implementation → verification.
What They Are For
- Translate requirements into system structure
- Align developers and engineers before implementation
- Define interfaces, data flows, and responsibilities
- Reduce ambiguity in complex systems
- Provide traceability back to requirements
Typical Structure
- Overview — purpose, scope, assumptions, constraints
- Requirements reference — links to relevant requirements (traceability matrix optional)
- High-level architecture — components, responsibilities, data flow
- Detailed design — data structures, state machines, algorithms, interface definitions
- Edge cases and failure handling — recovery strategies, validation rules
- Non-functional considerations — performance, security, maintainability, scalability
- Open questions / decisions — design trade-offs, alternatives considered
What a Design Document is NOT
- Not a requirements document
- Not a step-by-step implementation script
- Not code (though diagrams and pseudocode are fine)
See also: Requirements Engineering, Pharma Automation Framework