Requirement specification versus system specification separates the client's needs from the supplier's implementation response.
What is the difference?
The requirement specification describes what the client needs and why. The system specification explains how and with what the supplier will implement those requirements.
| Requirement specification | System specification | |
|---|---|---|
| Owner | client or appointed planner | supplier |
| Question | what and why? | how and with what? |
| Purpose | tender and comparison | implementation basis |
Quality rules
- Number and version requirements.
- Separate function, constraint and acceptance evidence.
- Keep dependencies, contradictions and open points visible.
- Preserve solution freedom where no justified constraint exists.
Current framework
The valid VDI/VDE 3694:2014-04 provides a structure for automation systems. A revision is in progress; the announced project is not yet a valid new edition.
Application: WMS requirement specification.
Applying Requirement and system specification in a project
Requirement and system specifications are connected through stable requirement IDs, version control, ownership and testable acceptance evidence.
Before applying Requirement and system specification, define the objective, system boundary and decision to be supported. The distinction from adjacent methods and systems is equally important: which processes are included, which interfaces remain outside the scope and which metrics indicate an improvement? This prevents a term from becoming a label and avoids local optimisation that creates new problems elsewhere.
A reliable assessment of Requirement and system specification combines current-state data with documented assumptions. Sources, reference periods, units and exceptions need to be transparent. Alternatives or measures can then be compared using consistent criteria. Depending on the task, these include performance and cost as well as space, inventory, ergonomics, quality, feasibility, risk and expandability.
The output from applying Requirement and system specification should support a concrete decision or a verifiable next step. Ownership, a target value and a review date make the expected effect measurable. To transfer the concept to a real assignment, connect it with the relevant consulting, planning, optimisation and digital capture services.
Requirement and system specification in practice: Our services overview brings together the relevant planning and consulting approaches.