Requirements
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A requirement is a formalized (documented) statement that describes what a system must provide, the level of quality it must achieve, or the physical/operational properties it must possess. It is formulated in such a way that it can be unambiguously linked to an original user need and subsequently tested (verified).
Types of Requirements
Types of requirements:
- Functional requirements: Define what a given system element must do.
- Accuracy requirements: Define the quantitative parameters of the corresponding functions performed by the system.
- Constraint requirements: Arise from limitations related to the operational mode, environmental conditions, safety, or regulatory compliance.
- Verification requirements: Ensure the level of confidence that the system possesses the specified characteristics in its real operating environment.
- Interface requirements: Define the functions, characteristics, tolerances, and limitations of all interfaces.
- Operational requirements: Define the operational capability of the system and its interaction with users.
SMART
The acronym SMART is used as a mnemonic for the characteristics of good requirements.
- Specific — The requirement describes only one function or characteristic of the system, stating what and how well it must be performed, without specifying the implementation method.
- Measurable — The parameter is expressed objectively: as a number, range, tolerance, or another verifiable criterion that allows for unambiguous confirmation of its fulfillment.
- Achievable — Fulfillment is realistic given the available technology, timeline, and budget, with an acceptable level of risk.
- Relevant - The requirement must be appropriate for the selected system level.
- Traceable — The requirement has a unique identifier and a documented source; it is logically linked to higher-level requirements and the need that generated it, ensuring bidirectional traceability.
External links
See also
Bibliography
- ISO/IEC/IEEE 29148:2018 “Systems and Software Engineering — Requirements Engineering”
- ISO/IEC/IEEE 15288:2023 “System Life-Cycle Processes”
- PMI: Requirements Management — A Practice Guide, 2015
- INCOSE Guide to Writing Requirements, 2023