Functional Specification (FS)
The Functional Specification (FS) describes how the product’s features are organized and how they work in detail. It breaks down the system into three levels — Requirements → Features → Specifications to design how the product works in detail. The FS also serves as the foundation for Information Architecture (IA).
Two viewing modes are available:
Tree View – visualize the overall structure at a glance.
Directory View – manage detailed policies and descriptions efficiently.
1. Understanding the Structure
The Functional Specification consists of three levels: Requirements → Features → Detailed Specifications
Requirement
Represents the high-level goals or user needs of the project.
e.g., “Member Management,” “Payment & Billing”
Acceptance Criteria
Define the conditions or policies that must be satisfied for the requirement to be considered complete, typically in checklist form.
e.g., “Users can sign up via email,” “Menu layout changes depending on user role”
Feature
Represents a specific function that fulfills a requirement.
e.g., “Sign Up,” “Document Sharing,” “Payment Management”
User Role
You can assign a responsible role to each feature, using the roles defined in the PRD.
e.g., “Planner,” “Manager,” “Guest”
Importance
Set the priority or importance of each feature. (Low / Medium / High)
Specification
Defines the specific actions or policies within each feature.
e.g., “Email Sign-Up,” “Change Password,” “Session Management”
Specifications are directly linked to pages in the Information Architecture (IA).
2. Switching Views
You can switch between different viewing modes using the toolbar buttons at the bottom of the FS tab.
Tree View
Get a full view of the functional hierarchy at a glance. Requirements, features, and specifications are displayed as connected nodes. This view is useful when you want to quickly understand the overall structure or review relationships between features.
Directory View
Explore and manage items step by step. The hierarchy — Requirement → Feature → Specification — is displayed as a structured list. Selecting an item opens detailed information on the right panel, where you can review and edit it. Edits to Acceptance Criteria or assigned user roles are made in the Directory View.
3. Adding & Editing
Editing in Tree View
Select a node and click the edit (✏️) icon at the top to enter edit mode. You can also double-click the node to edit it.
Editable fields vary by node type:
Requirement – name, description
Feature – name, importance, user role
Specification – name only
To add a new child node, select a node and click the “＋” button that appears on the right.
Hold Shift and click a node to open it directly in the Directory View.
Editing in Directory View
Click the “＋” button at the top of each section (Requirement / Feature / Specification) to add a new item.
Double-click any list item to rename it.
Select an item to edit its name, description, and detailed info in the right panel.
Use the Edit or Delete buttons on the right to manage items. When deleting, note that all sub-items will also be removed.
TIP : In the Directory View, you can drag and drop items to adjust their connections or reorder them.
4. Ask AI
Click the '+' button on the left side of an item, then use the 'Generate with AI' feature to create sub-items.
When the AI updates an item, a blue highlight icon appears in the Tree View. Click it to preview the changes in the Directory View.
Review and approve / reject each change, or approve / reject all at once using the buttons at the bottom.
Click the chat icon on the left panel to open the AI assistant and discuss revisions directly.
While selecting items in the Tree or Directory View, you can provide context to the chat so the AI follows more precise instructions.
Note: During AI generation, some items may be left unlinked if their parent connections are missing. In that case, review the unlinked items in the Directory View and drag and drop them to reconnect manually.
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