# Key Collection API - External References Description

## external_references structure

| Name | Type | Description | Example |
|  --- | --- | --- | --- |
| sequence | Integer | Index number of current reference in the list (used to set order) | 1 |
| type | String | Type of the reference. At the moment only "image_service" is supported | image_service |
| references | Object | Keys with external references. At the moment only "photo_id" reference is supported. | `{ "photo_id": 123 }` |