# Production

> The production optional block of a .well file: a list of Production objects.

Property `production` of the .well root, an array of objects, optional. [Defined in the spec](/format/spec/v2/object-schemas#production-since-v23).

### `meter_reading`

| Field | Type | Required | Values / constraints | Description |
| --- | --- | --- | --- | --- |
| `id` | string | yes |  |  |
| `type` | string | yes | = `meter_reading` |  |
| `corrects` | string | no |  |  |
| `sequence` | integer | no |  |  |
| `notes` | string | no |  |  |
| `datetime` | string | yes | pattern `^\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}(\.\d+)?(Z\|[+-]\d{2}:\d{2})$` |  |
| `meter_id` | string | yes |  |  |
| `reading` | number | yes | >= 0 |  |
| `source` | string | no |  |  |

### `estimated_volume`

| Field | Type | Required | Values / constraints | Description |
| --- | --- | --- | --- | --- |
| `id` | string | yes |  |  |
| `type` | string | yes | = `estimated_volume` |  |
| `corrects` | string | no |  |  |
| `sequence` | integer | no |  |  |
| `notes` | string | no |  |  |
| `period_start` | string | yes | pattern `^\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}(\.\d+)?(Z\|[+-]\d{2}:\d{2})$` |  |
| `period_end` | string | yes | pattern `^\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}(\.\d+)?(Z\|[+-]\d{2}:\d{2})$` |  |
| `volume` | number | yes | >= 0 |  |
| `method` | string | no |  |  |

### Custom type (`x-` prefix)

| Field | Type | Required | Values / constraints | Description |
| --- | --- | --- | --- | --- |
| `id` | string | yes |  |  |
| `type` | string | yes |  |  |
| `corrects` | string | no |  |  |
| `sequence` | integer | no |  |  |
| `notes` | string | no |  |  |