---
title: "Functional Requirements"
description: "Template for documenting functional requirements"
template-type: "requirement"
related-templates: 
  - "system-overview"
  - "user-stories"
  - "traceability"
---

## Template Structure

### 1. Requirement Definition
- ID and title
- Description
- Priority and source
- Dependencies

### 2. Behavioral Specifications
- Detailed behaviors
- Constraints
- Exception cases

### 3. Traceability
- Related user stories
- Implementation references
- Test cases

## Functional Requirement Structure

### Basic Format
**FR-[XXX]**: [Requirement Title]

**Description**: [Brief description of the requirement]

**Details**:
- [Specific behavior 1]
- [Specific behavior 2]
- [Specific behavior n]

**Priority**: [Must have | Should have | Could have | Won't have]  
**Source**: [Source reference]  
**Dependent requirements**: [List of related requirements]  
**Verification method**: [Testing approach]

### Example
**FR-103**: User Authentication

**Description**: The system must authenticate users before granting access to protected resources.

**Details**:
- The system shall provide a login interface requiring username and password
- The system shall validate credentials against the user database
- The system shall enforce password complexity requirements
- The system shall lock accounts after 5 failed login attempts
- The system shall provide a password recovery mechanism

**Priority**: Must have  
**Source**: Security policy SP-42  
**Dependent requirements**: FR-101, FR-102  
**Verification method**: Security testing

**Implementing Stories**:
- \@story:E01-F01-US01 - New customer account creation
- \@story:E01-F01-US02 - Password reset flow

## Traceability Tags

Use these tags to establish requirement relationships:
- `@source`: Source document/stakeholder
- `@implements`: Design document reference
- `@depends-on`: Dependencies on other requirements
- `@extends`: Requirements this one extends
- `@related-to`: Related requirements

## Validation Checklist

Before finalizing a functional requirement:

- [ ] Unique identifier assigned
- [ ] Clear, unambiguous description
- [ ] Specific, measurable behaviors listed
- [ ] Priority level defined
- [ ] Dependencies identified
- [ ] Verification method specified
- [ ] Traceability links established

## User Story Mapping

### Story References
**Implemented By**:
- E01-F01-US01: Account Creation Story
- E01-F01-US02: Password Reset Story

## Cross-Reference Matrix

| Requirement ID | User Stories | NFRs |
|---------------|--------------|------|
| FR-103 | E01-F01-US01, E01-F01-US02 | NFR-201, NFR-202 |