Concept: Types of Requirements
A requirement type is simply a class of requirements that enable teams to organize large numbers of requirements into meaningful and more manageable groups. Establishing different types of requirements in a project helps team members classify requirements and communicate more clearly.
Main Description

Traditionally, requirements are looked upon as statements of text fitting into one of the categories mentioned in Concept: Requirements. Each requirement states "a condition or capability to which the system must conform".

To perform effective Requirements Management, we have learned that it helps to extend what we maintain as requirements beyond only the detailed "software requirements". We introduce the notion of requirements types to help separate the different levels of abstraction and purposes of our requirements. 

Software Requirement Specifications Test Suites Desing Model Supplementary Specification Use-Case Model Stakeholder Requests Vision Concepts: Requirements

We may want to keep track of ambiguous "wishes", as well as formal requests, from our stakeholders to make sure we know how they are taken care of. The Vision document helps us keep track of key "user needs" and "features" of the system. The Use-Case Model is an effective way of expressing detailed functional "software requirements", therefore use cases may need to be tracked and maintained as requirements, as well as perhaps individual statements within the use case properties which state "conditions or capabilities to which the system must conform". Supplementary Specifications may contain other "software requirements", such as design constraints or legal or regulatory requirements on our system. For a complete definition of the software requirements, use cases and Supplementary Specifications may be packaged together to define a Software Requirements Specification (SRS) for a particular "feature" or other subsystem grouping.

The larger and more intricate the system developed, the more expressions, or types of requirements appear and the greater the volume of requirements. "Business rules" and "vision" statements for a project trace to "user needs", "features" or other "product requirements". Use cases or other forms of modeling and other Supplementary Specifications drive design requirements, which may be further decomposed to functional and non-functional "software requirements" represented in analysis & design models and diagrams.

More Information

More Information on this topic can be found at:

Concept: Requirements
Concept: Requirements Management
Concept: Traceability
Whitepaper: Applying Requirements Management with Use Cases