INCOSE Guide to Writing Requirements: a practical review

Which guide should you use?

The official INCOSE store lists Guide to Writing Requirements, version 4, updated July 2023. Get the guide from INCOSE; the publisher also provides a characteristics summary. This page is an applied example, not a reproduction of the guide.

Review a requirement with these questions

Use this working checklist alongside the official guide:

• What entity has the obligation, and under which conditions?
• What observable result is required? Could two teams interpret it differently?
• Does the statement combine promises that need separate decisions or checks?
• Are limits, units, timing points and exceptional conditions defined?
• Where did the promise come from, and who can approve it?
• Does it conflict with another requirement or rely on an unreviewed assumption?

Write the missing decision down before polishing the wording. An SRS organizes the resulting requirements; acceptance criteria make individual outcomes observable.

Use the guide as a review aid

The INCOSE Guide to Writing Requirements addresses characteristics of individual statements and sets of requirements, writing rules, and supporting attributes. The official guide description and characteristics summary distinguish concerns such as clarity, singularity, feasibility, verifiability, and consistency.

Use those concerns to ask concrete questions about the requirement in front of you. A style score cannot supply a missing operating limit or choose between conflicting business needs.

Work one sentence into a testable decision

The numbers are illustrative proposed targets. The responsible authority must decide whether they are necessary and feasible. Reliability is still unresolved: specify the relevant failures, recovery behavior, and data-loss expectations separately rather than treating one latency measure as the whole promise.

Record what the sentence depends on

Define the load profile, request mix, hardware or deployment scope, warm-up period, timing points, and excluded conditions. Preserve the source and rationale for the target. Otherwise two teams can agree with the sentence while measuring different things.

Review the set as well as the individual statement. A latency target may conflict with durability, safety, or cost requirements. The accepted tradeoff belongs in the requirement record and its relationships, not only in a meeting or task transcript.

Connect the review to implementation evidence

proof gaps specs/system --check quality
proof validate
proof review req SYS-REQ-042

Proof's quality analysis and schema validation provide bounded automated checks. The review brief collects the requirement and available evidence. None of these commands claims complete conformance to the INCOSE guide or establishes product acceptance by itself.

After resolving intent, choose tests or analysis that observe the stated target, retain version and environment information, and review the result. A clear statement, an approved statement, and a satisfied statement are three different states.

Continue from here

Review requirement quality. Make quality targets observable.

Bring a vague requirement and the decision or measurement it currently leaves open. Bring a change to Proof.