> For the complete documentation index, see [llms.txt](https://docs.abtasty.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.abtasty.com/server-side/command-line-interface/resource-loader/feature-experimentation/variation.md).

# Variation

#### Definition

A **Variation** is a traffic bucket inside a variation group. Exactly one variation per group is the **reference** (control). Non-reference variations may define **Modifications** (e.g., setting feature flags or remote config variables) applied to users assigned to that variation.

#### Payload Properties

When creating/updating a Variation, the payload includes the following fields:

* **`id`** (String, *optional*) – The variation unique ID. Include this only when updating an existing variation.
* `name` (String, **required**) — Label for the variation.
* `reference` (Boolean, **required**) — Exactly one `true` per group.
* `allocation` (Integer, **required**) — Percentage (0–100) of the group’s traffic.
* `modifications` (Object, optional) — Changes applied to this variation:
  * `type` (String, **required when present**) — e.g., `"FLAG"` (or `"VARIABLES"` if supported).
  * `value` (Object, **required when present**) — Key/value pairs to set (flag names or config keys).

**Example Variation Payload:** Creating a new variation with a name, allocating 50% of traffic, and including some flags:

```json
{
  "name": "Variation 1",
  "reference": false,
  "allocation": 50,
  "modifications": {
    "type": "FLAG",
    "value": {
      "flag_created_with_resource_loader": "blue",
      "recommendations.limit": 6
    }
  }
}

```

#### Response Fields

When a Variation is returned by the API/Resource Loader (nested under its variation group), you’ll see the server-assigned ID and the resolved definition:

* `id` (String) — Unique variation identifier.
* `name` (String) — Variation name.
* `reference` (Boolean) — Whether this is the control.
* `allocation` (Integer) — Traffic allocation (0–100).
* `modifications` (Object) — Resolved modifications:
  * `type` (String) — e.g., `"FLAG"`.
  * `value` (Object|Array) — Effective values. Some implementations return an empty object/array for the control when no changes apply.

**Example Response**

```json
{
  "allocation": 50,
  "id": "variation_id",
  "modifications": {
    "type": "FLAG",
    "value": []
  },
  "name": "Original",
  "reference": true
}
```

#### Error Codes

Variations use the same set of error codes as modifications (and other resources), adjusted to the context of campaigns and variations:

* **InvalidPayload** – The variation data was missing required fields or had invalid values.
* **ParentNotFound** – The specified parent campaign was not found (e.g., the `$_parent_id` campaign ID is invalid).
* **PermissionDenied** – The user is not allowed to create or modify variations in this campaign.
* **DuplicateRef** – A variation with the same reference already exists (for example, a duplicate variation name in the same campaign).
* **InvalidDependency** – A related resource is missing (for instance, trying to create a variation in a campaign that doesn’t exist or isn’t accessible).


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