FS Writing Guide
We’ve prepared this guide to help you quickly understand how to write Functional Specifications (FS) in Manyfast.
Let’s imagine a situation where you’re planning an online shopping service, and build out the key features required for shopping.
Prepare a New Document
Create a new document, then switch to the Directory View.
This guide mainly uses the Directory View, where you can focus on each function individually and write in more detail.
📌 Tip
Hold Shift + Click on an item in Tree View to jump directly to it in Directory View.
Double-click an item to rename it instantly.
You can drag and drop to reorder or change the parent hierarchy.
How to write Requirements
Let’s start by defining the requirements.
Example: Shopping
When running a shopping service, customers need to browse and order products. Write down the essential goals or conditions that must be satisfied for “shopping” to work properly.
Example acceptance criteria:
Users should be able to select categories or brands.
Users should be given sorting options.
Users should be able to search for products by keyword.
Search results should include related tags or filters.
Users should be able to purchase within the service.
Users should be able to add products to a cart and apply combined benefits.
Depending on the project, you can write requirements at different levels — for example: minimum viable function, user journey completion, or business goal achievement.💭
Why define acceptance criteria?
It helps clarify the product’s purpose and key user flows.
It also serves as a benchmark for measuring progress and completeness throughout development.
✏️In Manyfast, it looks like this:
How to write Features
Next, break down the requirements into specific features.
Think about questions like:
“What functions are typically part of shopping?”
“What features are needed to meet this requirement?”
Then, list them out in concrete terms.
For example, based on our “Shopping” requirement, you might define “Browse Product List” as a core feature since it includes actions like browsing by category, sorting, and searching.
✏️In Manyfast, it looks like this:
How to write Specifications
Now, let’s break down the Browse Product List feature into its detailed specifications. To make it clearer, we’ll use familiar shopping interactions as examples.
Browse Product List
Displays a list of products.
Filter
By category (2 levels) or brand
Sort
By recommendation, price, or popularity
Search
Searches by product name; applies same filter rules
View Product Details
Displays detailed information of selected item
Option / Quantity Selection
Allows price changes by option
Add to Cart
Includes selected options and quantity
Purchase Now
...
You can write these detailed behaviors under each feature.
📌 Tip : Use the Description field in Manyfast to record notes or policies for each item.
✏️In Manyfast, it looks like this:
Iteration
That’s the basic writing flow.
Once you finish writing in Directory View, switch to Tree View to see how everything connects visually.
At this stage, just keep expanding your ideas step by step — you’ll gradually complete the full structure of your product.
📌 Remember: There’s no such thing as a perfect plan from the start. Refine and iterate — that’s how great planning happens.
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