# Single Relation

The Single Relation labeling tool allows you to create a relation between two annotations.

{% hint style="info" %}
The Single Relation tool is supported across the Audio, Image, Video, DICOM, PDF, and Text labeling editors.
{% endhint %}

![](https://3895963154-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FTcOUG6rfWxqGM0N4db2P%2Fuploads%2FSPjmWoAC1fn3xDLRwMig%2FScreen%20Shot%202021-10-15%20at%2015.32.51.png?alt=media\&token=40552641-928d-4268-88e4-54465d32cd28)

{% hint style="info" %}
Single relations are not visible unless the user is hovering over them with the mouse cursor.
{% endhint %}

## How to add a Single Relation tool to your project <a href="#how-to-add-a-bounding-box-tool-to-your-project" id="how-to-add-a-bounding-box-tool-to-your-project"></a>

From the project’s *Settings* tab, enter the *Label Set* section.

Click on *Add Category*. From the list that appears, click on *Single Relation*.

A new row will appear named *Single Relation*. Click on it to expand it.

![](https://3895963154-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FTcOUG6rfWxqGM0N4db2P%2Fuploads%2FcCkT3hHuWZj60pOlYroE%2FScreen%20Shot%202021-10-15%20at%2015.31.25.png?alt=media\&token=27d21473-7a34-4e9b-886e-40857ae3b9f1)

Give your single relation tool a title and description.

Enable the *Required* toggle if you want to force labelers to create a single relation for each asset. When the toggle is disabled, labelers will be able to save and move to the next asset without creating the single relation.

### How to Draw a Single Relation <a href="#how-to-draw-a-bounding-box" id="how-to-draw-a-bounding-box"></a>

Click on the label where you’d like the single relation to start. Click on the second label where you’d like the relation to end. Press N on your keyboard to finalize the relation.

<figure><img src="https://3895963154-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FTcOUG6rfWxqGM0N4db2P%2Fuploads%2FaqaZwBudClEMMscvvkYM%2FKapture%202024-05-16%20at%2013.50.28.gif?alt=media&#x26;token=267f2946-ba7a-43b5-b024-986204e631e2" alt="" width="557"><figcaption></figcaption></figure>

After having created the relation, you can change its direction by clicking on the <img src="https://3895963154-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FTcOUG6rfWxqGM0N4db2P%2Fuploads%2FjBRzTewqT2sPNh9WPJnn%2Fimage.png?alt=media&#x26;token=8ebef3e2-8aa0-4792-8768-fa1203c546fe" alt="" data-size="line"> small arrow inside the relation's box.

#### Single Relation Directions

* **Forward:** the first label points at the second label.
* **Backward:** the second label points at the second label.
* **Bidirectional:** The labels point at each other.