> For the complete documentation index, see [llms.txt](https://help.glpi-project.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://help.glpi-project.org/readme-1/field_unicity.md).
# Fields unicity
To avoid duplicates, the **`uniqueness of fields`** function allows you to refuse hardware imports if one of the fields set is identical to another field of the same type of hardware. For example, 2 computers with the same serial number.
* From **`setup`** > **`field unicity`**, click on **`add`**
* Add a :
* a **`name`**
* A **`comment`** (optional)
* Set **`active`** to **`yes`**
* The **`type`** of item targeted (computer, telephone, user, etc.)
* Select the **`filed`** that will be considered unique
* Indicate whether the **`import`** should be **`refused`** or **`accepted`**.
* Indicate whether a **`notification`** should be sent
{% hint style="warning" %}
**Sub-entity**
If necessary, remember to tick **`sub-entity`** in the top right-hand corner so that your field can be checked in all the sub-entitles in which uniqueness is created.
{% endhint %}
If a duplicate is created, an error message will appear:
---
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