The Software Requirements Document

What is document variability?

Information in the requirements document depends on the type of system and the approach to development used. Systems developed incrementally will, typically, have less detail in the requirements document. Requirements documents standards have been designed but these are mostly applicable to large systems engineering projects.

What is the structure of a requirements document?

Preface, introduction, glossary, user requirements definition, system architecture, system requirements specification, system models, system evolution, appendices and index.

What is in the index in a requirements document?

Several indexes to the document may be included. As well as a normal, alphabetic index there may be an index of diagrams, an index of functions and so on.

What do system customers do with the Software Requirements Document?

Specify the requirements and read them to check that they meet their needs. Customers specify changes to the requirements.

Who uses the Software Requirements Document?

System customers, managers, system engineers, test engineers and maintenance engineers.

What is in the appendices in a requirements document?

These should provide detailed, specific information that is related to the application being developed such as hardware and database descriptions. Hardware requirements define the minimal and optimal configurations for the system. Database requirements define the logical organisation of the data used by the system and the relationships between data.

What do managers do with the Software Requirements Document?

They use the requirements document to plan a bid for the system and to plan the system development process.

What do system test engineers do with the Software Requirements Document?

They use the requirements to develop validation tests for the system.

What do system maintenance engineers do with the Software Requirements Document?

They use the requirements to understand the system and the relationships between its parts.

What do system engineers do with the Software Requirements Document?

They use the requirements to understand what system is to be developed.

What is in the system architecture in a requirements document?

This chapter should present a high-level overview of the anticipated system architecture, showing the distribution of functions across system modules. Architectural components that are reused should be highlighted.

What is in the system models in a requirements document?

This might include graphical system models showing the relationship between the system components and the system and its environment. Examples possible models are object models, data-flow models, or semantic data models.

What is in the preface in a requirements document?

This should define the expected readership of the document and its version history, including rationale for the creation of a new version and a summary of the changes made in each version.

What is in the glossary in a requirements document?

This should define the technical terms used in the document. You should not make assumptions about the experience or expertise of the reader.

What is in the system requirements specification in a requirements document?

This should describe the functional and nonfunctional requirements in more detail. If necessary, further detail may also be added to the nonfunctional requirements. Interfaces to other systems may be defined.

What is in the system evolution in a requirements document?

This should describe the fundamental assumptions on which the system is based, and any anticipated changes due to hardware evolution, changing user needs etc. This section is useful for system designers as it may help them avoid design decisions that would constrain likely future changes to the system.

What is in the introduction in a requirements document?

This should describe the need for the system. It should briefly describe the systems functions and explain how it will work with other systems. It should also describe how the system fits into the overall business or strategic objectives of the organisation commissioning the software.

What is in the user requirements definition in a requirements document?

This should describe the services provided for the user. The nonfunctional system requirements should also be described in this section. This description may use natural language, diagrams, or other notations that are understandable to customers. Product and process standards that must be followed should be specified.