# WellId

> The well_id optional block of a .well file: a list of WellId objects.

Property `well_id` of the .well root, an array of objects, optional. [Defined in the spec](/format/spec/v2/format-reference#well_id).

| Field | Type | Required | Values / constraints | Description |
| --- | --- | --- | --- | --- |
| `authority` | string | yes |  |  |
| `id` | string | yes |  |  |
| `primary` | boolean | no |  |  |