A Software Requirement Specification (SRS) document serves as the foundation for software development. A well-prepared SRS ensures that the final product meets user needs while maintaining high quality, security, and performance. Below are the key properties of a good SRS document:
1. Correctness
📌 The SRS document should accurately reflect the client’s and users’ requirements.
📌 Every requirement should be precisely defined and approved by stakeholders.
Example:
- Incorrect: “The system should load quickly.” (Vague)
- Correct: “The system should load within 2 seconds for 95% of users under normal conditions.”
2. Completeness
📌 The document should cover all functional and non-functional requirements.
📌 No feature or expectation should be left out.
📌 Every section (scope, constraints, interfaces) must be well-defined.
Example:
- If the software involves user authentication, the SRS must specify:
- Login mechanism (username/password, OTP, biometric, etc.).
- Password recovery process.
- Security measures (e.g., encryption, session timeout).
3. Unambiguity
📌 Requirements must be clear and precise to avoid misunderstandings.
📌 Avoid vague terms like “fast,” “efficient,” or “user-friendly” unless quantified.
Example:
- Ambiguous: “The system should be user-friendly.”
- Clear: “The system should allow users to complete a registration form within 2 minutes, with auto-suggestions for common fields.”
4. Consistency
📌 No contradictions should exist within the document.
📌 Terminology and descriptions should remain uniform throughout.
Example:
- Inconsistent Requirement:
- Page 10: “The system should support Windows only.”
- Page 15: “The system should be compatible with Windows and macOS.”
✅ Fix: Clearly specify whether macOS support is required or optional.
5. Verifiability
📌 Every requirement must be testable through inspection, demonstration, or analysis.
📌 Avoid subjective statements that cannot be measured.
Example:
- Non-Verifiable: “The software should be highly secure.”
- Verifiable: “The software should use AES-256 encryption for password storage and require two-factor authentication (2FA) for admin login.”
6. Modifiability
📌 The SRS should allow for easy updates when new requirements arise.
📌 Requirements should be written in a structured and modular format.
Example:
- Instead of mixing security, UI, and performance requirements, separate them into different sections.
- Use numbering (FR1, FR2, NFR1, etc.) to allow easy tracking of modifications.
7. Traceability
📌 Each requirement should be traceable to its source (business need, stakeholder request).
📌 Use a traceability matrix to link requirements with design, testing, and implementation phases.
Example Traceability Matrix:
| Requirement ID | Description | Source | Test Case ID |
|---|---|---|---|
| FR1 | User login with OTP verification | Client Request | TC1.1 |
| FR2 | Password reset via email link | Business Analyst | TC1.2 |
8. Feasibility
📌 The requirements should be practical and achievable given the project’s constraints.
📌 Avoid unrealistic demands on technology, budget, or timelines.
Example:
- Infeasible Requirement: “The system should respond instantly to all user requests, even under high load.”
- Feasible Requirement: “The system should respond within 2 seconds for 95% of users when handling up to 500 concurrent users.”
9. Conciseness
📌 The document should be concise but complete – no unnecessary repetition or lengthy explanations.
📌 Use diagrams, tables, and bullet points instead of lengthy paragraphs.
Example:
- Instead of:
- “The system will allow the user to register by entering their name, email, phone number, and password. The system will then send an email verification to confirm the registration.”
- Better:
- Registration Process:
- User enters name, email, phone number, and password.
- System sends email verification link.
- User clicks the link to activate the account.
- Registration Process:
10. Structured Format
📌 The document should follow a standard format (like IEEE 830) for easy navigation.
📌 Sections should be logically arranged (Introduction → Requirements → Constraints → Interfaces).
✅ Example Standard SRS Format:
- Introduction
- Overall Description
- Functional Requirements
- Non-Functional Requirements
- External Interfaces
- Constraints
- Appendices & References
Summary Table: Properties of a Good SRS
| Property | Description | Example |
|---|---|---|
| Correctness | Accurately represents stakeholder requirements | Clearly defined system objectives |
| Completeness | Covers all functional and non-functional aspects | No missing features |
| Unambiguity | Uses clear, well-defined terms | “Response time ≤ 2 sec” instead of “Fast response” |
| Consistency | No contradictions in different sections | Same terminology throughout the document |
| Verifiability | Requirements can be tested | “Must support AES-256 encryption” |
| Modifiability | Easy to update when changes occur | Organized in sections with numbering |
| Traceability | Links each requirement to its source | Traceability matrix |
| Feasibility | Realistic and achievable requirements | Handles 500 users, not “unlimited users” |
| Conciseness | No unnecessary details, easy to read | Bullet points, tables, diagrams |
| Structured Format | Follows IEEE 830 or other standard | Sections arranged logically |
Conclusion
A well-written SRS is critical for successful software development. It should be clear, complete, testable, and structured, ensuring that the software meets business needs, is easy to develop, and can be tested efficiently. By maintaining these properties, teams can minimize miscommunication, delays, and project failures.