# Functional requirements specification (FRS) example > A finished 13-page functional requirements specification, written by Ainna for VentureForce. Three pages are open here; the other ten stay closed. A finished example, not a template. Page: https://ainna.ai/documents/frs · Word · 13 pages · Document 11 of 12, the build · Updated 6 October 2026 · Document designs by George Krasadakis ## The pages on show - Page 1 of 13, Title page: The concept and what the system does, with the concept version and the product definition it was written against. Image: https://ainna.ai/images/examples/frs-example-01-1200.webp - Page 4 of 13, Rules, compliance, then the first area: The rules that hold across the system and where it meets regulation; then the first functional area, requirement by requirement. Image: https://ainna.ai/images/examples/frs-example-04-1200.webp - Page 12 of 13, Traceability: Every PRD requirement traced to the area that covers it, the requirements that specify it and the tests that verify it. Image: https://ainna.ai/images/examples/frs-example-12-1200.webp The other 10 pages stay closed. ## What is a functional requirements specification (FRS)? A functional requirements specification (FRS) defines, testably, how a system must behave: business rules, validations, exceptions, interfaces and acceptance tests, each traced to the PRD. Also called a functional specification (FS or FSD); close to what ISO/IEC/IEEE 29148 calls a software requirements specification (SRS). For software, digital and integration concepts. Also called: FRS, Functional specification, FS, FSD, Functional requirements document. ## Why it matters User stories say what people need. Engineers and testers need to know what the system does in every case. The FRS states every rule and every exception, so the team builds and tests against one text, and every requirement traces back to the reason it exists. ## How the specification is built Ainna writes the FRS from the PRD and from a model of the system, so nothing in it is invented on the way. 1. **Scope.** A check of the concept: software, a digital service or an integration, and what is in and out. In Ainna's document: purpose, audience and scope. 2. **The system model.** Its actors, capabilities, components, interfaces and data. In Ainna's document: actors, roles and permissions; interface behaviour. 3. **The requirements.** Each functional area, requirement by requirement, with its business rules, validations, inputs, outputs and exceptions. In Ainna's document: each functional area, requirement by requirement. 4. **The tests.** Acceptance and test conditions for each requirement. In Ainna's document: acceptance and test conditions. 5. **Traceability.** Every PRD requirement traced to the area that covers it, the requirements that specify it and the tests that verify it. In Ainna's document: traceability to the PRD. ## What's inside - Purpose, audience and scope - Actors, roles and permissions - Rules that hold across the system - Compliance touchpoints - Each functional area, requirement by requirement - Business rules and validations - Inputs, outputs and data handling - Exceptions and system responses - Interface behaviour - Acceptance and test conditions - Traceability to the PRD - Assumptions and glossary ## Where it comes from Distilled from the PRD's requirements, a check of the concept's scope, and a system model of its actors, capabilities, components, interfaces and data. Comes after: [Product Requirements Document (PRD)](https://ainna.ai/documents/prd) Leads to: [System Analysis, Design and Architecture](https://ainna.ai/documents/architecture) ## Questions **Is an FRS the same as an SRS?** Close, and many teams use the names interchangeably. ISO/IEC/IEEE 29148, the international standard for requirements engineering, calls the software-level document a software requirements specification (SRS) and gives it all of a system's requirements, functional and non-functional. An FRS, also called a functional specification (FS or FSD), concentrates on the functional side: how the system must behave, rule by rule, with its validations, exceptions, interfaces and acceptance tests. Ainna's FRS traces each of these to the PRD, and its architecture document carries the quality targets. **What is the difference between a BRD and an FRS?** A business requirements document (BRD) states what the business needs and why, in the business's own terms. An FRS turns those needs into exactly how the system must behave, testably, for the people who build and test it. In banking, insurance and enterprise IT the two usually come as a pair. In Ainna, the PRD plays the BRD's part, with the business case, the users and the requirements, and the FRS traces every requirement back to it. **Who writes and signs off an FRS?** Usually a business analyst or product owner writes it with the engineering lead. Product signs off the behaviour; engineering and QA sign off that it can be built and tested. **How detailed should an FRS be?** Detailed enough that two engineers would build the same behaviour, and a tester could write a test for each requirement without asking. ## Links - The problem behind the idea: [Problem 0032 on Problem Radar](https://ainna.ai/problems/workforce-unprepared-for-the-disruption-ai-is-bringing) - All twelve documents: https://ainna.ai/documents (Markdown: https://ainna.ai/documents.md) ## Clarity, by design Every document is architected and designed for one purpose: clarity. The designs are original, built on the method of Innovation Mode 2.0 (Springer Nature, 2026), where some of them are published. Its author, George Krasadakis, has spent 25 years building products, in a career that spans Microsoft, Accenture, GSK and ResMed. Ainna distils your work into each one: every claim in its place, every figure with its source or its assumption. Decks are set in Roboto, documents in Georgia. ## About the sample It comes from one public problem, number 0032 on Problem Radar (https://ainna.ai/problems/workforce-unprepared-for-the-disruption-ai-is-bringing), which Ainna framed and developed into one idea, VentureForce. It is a concept, not a company; its market figures are AI estimates.