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# 🟦 Not

# 🟦 Not

${frame}[Video: anatomy of the Not block](https://celestory-docs-videos.netlify.app/en/anatomie-bloc/not.html)

![Not](https://celestory-docs-illustrations.netlify.app/en/Not_EN.svg)

The Not block flips a Boolean value (True/False): True becomes False, and False becomes True — like a switch that reverses itself.

It's useful whenever you want to trigger something only when a condition is NOT true.

## 📥 Inputs

- value (Boolean): The Boolean value to invert, which may come from a condition or a variable.

## 📤 Outputs

- value (Boolean): The inverted value (True becomes False, False becomes True).

## 💡 Example of use

Scenario: Prevent access to a secure area without a badge

1. A user attempts to open a secure door.
1. The system checks if the variable aBadge is True (the user has a valid badge).
1. The value of aBadge is connected to the value input of the Not block.
1. The output of the Not block is linked to a condition that triggers an alert.
1. Behavior:

- If aBadge = False (no badge), the Not block returns True → the alert is triggered.
- If aBadge = True (valid badge), the Not block returns False → access is authorized.

## ⚙️ Technical Details

- Logic operation: Pure inversion (!value in programming), compatible only with Boolean data.
- Error handling: If a non-Boolean value is provided, the block returns False by default.

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*Documented version: v1*