SRSs are typically developed during the first stages of "Requirements Development," which is the initial product development phase in which information is gathered about what requirements are needed--and not.
You probably will be a member of the SRS team (if not, ask to be), which means SRS development will be a collaborative effort for a particular project. Several standards organizations (including the IEEE) have identified nine topics that must be addressed when designing and writing an SRS:
- Interfaces
- Functional Capabilities
- Performance Levels
- Data Structures/Elements
- Safety
- Reliability
- Security/Privacy
- Quality
- Constraints and Limitations
A sample of a basic SRS outline
- Introduction
1.1 Purpose
1.2 Document conventions
1.3 Intended audience
1.4 Additional information
1.5 Contact information/SRS team members
1.6 References
- Overall Description
2.1 Product perspective
2.2 Product functions
2.3 User classes and characteristics
2.4 Operating environment
2.5 User environment
2.6 Design/implementation constraints
2.7 Assumptions and dependencies
- External Interface Requirements
3.1 User interfaces
3.2 Hardware interfaces
3.3 Software interfaces
3.4 Communication protocols and interfaces
- System Features
4.1 System feature A
4.1.1 Description and priority
4.1.2 Action/result
4.1.3 Functional requirements
4.2 System feature B
- Other Nonfunctional Requirements
5.1 Performance requirements
5.2 Safety requirements
5.3 Security requirements
5.4 Software quality attributes
5.5 Project documentation
5.6 User documentation
- Other Requirements
Appendix A: Terminology/Glossary/Definitions list
Appendix B: To be determined
about the question,the manager and client are actor of a same system. So you should use one system for your project.