---
title: Use case
description: Actors and the use cases they take part in, inside a system boundary.
source: https://github.com/crabtalk/bezel/blob/main/crates/mermaid/src/diagrams/usecase/mod.rs
---

> One page of the bezel documentation. The index is https://bezel.gallery/llms.txt

# Use case

```mermaid
usecase-beta
direction LR
actor Customer("Customer")
actor Clerk("Clerk")
systemBoundary "Order system"
  Browse("Browse catalogue")
  Checkout("Place order")
  Refund("Issue refund")
end
Customer --> Browse
Customer --> Checkout
Clerk --> Refund
```

## Syntax

- `actor Name` declares an actor; `id("label")` a use case.
- `systemBoundary "name" … end` puts use cases inside a system.
- `a --> b` links an actor to a use case.
- `direction` sets the layout; `classDef`, `class` and `style` restyle.