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Synopsis of "The Contents of a Requirements Specification"

2.4 Major Nonfunctional Capabilities Section

The purpose of this section is to specify in detail the important nonfunctional aspects of the system: those that apply to the system as a whole. It’s hard to pin down the contents of this section because it depends very much on the nature of the system, so let’s tackle it by suggesting a process by which to write it:

  • Step 1: Create an empty “Major Nonfunctional Capabilities” section at the end of the requirements specification when first creating the specification. This serves as a reminder not to forget this area.

  • Step 2: Write the main body of the requirements specification. If, along the way, you identify any nonfunctional topic that’s too big to fit anywhere else, add it to the “Major Nonfunctional Capabilities” section.

  • Step 3: Consider whether there are any extra topics not yet specified. Concentrate on nonfunctional and peripheral aspects. Think especially about flexibility, quality, security, usability and accessibility, standards, and technology constraints.

  • Step 4: Move as much as you can of this section’s contents to other places in the specification.

  • Step 5: Reorganize this section, and give it the most suitable title.