# Reference designators

### Overview

* Define reference designators in the mBOM
* Install inventory into reference designator positions in the aBOM
  * aBOMs will fan out to represent the number of reference designators

### Example

In the assembly below, there are 8 lidar, 8 radar, and 3 camera sub components. 

<figure><img src="https://3615148728-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F-LkRqYp6lJhwxjYdzYG8%2Fuploads%2F61LhKyIv1w9axEkNstlK%2Fimage.png?alt=media&#x26;token=eea5a55a-3fb2-4cf2-867d-2f3e86f4ebcb" alt=""><figcaption></figcaption></figure>

To define positions for the camera click the `Add` button in the Reference Designators column as show below:

<figure><img src="https://3615148728-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F-LkRqYp6lJhwxjYdzYG8%2Fuploads%2FV3dzCdyYeFBfHwoe687b%2F2022-09-21%2011.41.20.gif?alt=media&#x26;token=8482055e-195a-4501-a63b-4ef5b6b02e22" alt=""><figcaption></figcaption></figure>

When the aBOM is generated, the reference designator will appear above the inventory selector for the camera items. Inventory can now be installed into specific positions. Note that 1 aBOM item was created for each reference designator.

<figure><img src="https://3615148728-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F-LkRqYp6lJhwxjYdzYG8%2Fuploads%2Fj643UN2ykqg9pac0ChKJ%2Fimage.png?alt=media&#x26;token=9e7cb097-6355-4128-93f1-b17117f2641d" alt=""><figcaption></figcaption></figure>

Reference designators are also reflected in the trace view:

<figure><img src="https://3615148728-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F-LkRqYp6lJhwxjYdzYG8%2Fuploads%2FJoDrOjKgsn5nGOD5xr2R%2Fimage.png?alt=media&#x26;token=de762a3c-dea3-4204-b521-e3f0a2357977" alt=""><figcaption></figcaption></figure>

### Rules/Validations

* You can not define more reference designators in the mBOM than quantity
* When creating aBOM items for reference designators, each aBOM item is created for quantity 1