# ColumnItem

One column of a tab's header row.

Type: object

Fields typed as another model are documented on that model's page; fetch it before filling the field.

| Field | Type | Required | Description | Allowed values / default / constraints |
| --- | --- | --- | --- | --- |
| `letter` | string | yes | Spreadsheet column letter — the value automation column fields take (`filter`, `split`, `remove_duplicates`, `left_join`, `anonymize`). |  |
| `index` | integer | yes | Zero-based column position. |  |
| `header` | string, nullable | no | The header cell exactly as stored (not trimmed — match it verbatim); null when the cell is empty. |  |

## Used by

- [GET /rest/beta/files/{provider}/{file_id}/structure](https://dev-api.sheetgo.com/rest/reference/files.md#get-rest-beta-files-provider-file-id-structure)
- [TabItem](https://dev-api.sheetgo.com/rest/reference/models/TabItem.md)

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More: start page https://dev-api.sheetgo.com/rest/reference.md, everything in one file https://dev-api.sheetgo.com/rest/llms-full.txt, OpenAPI https://dev-api.sheetgo.com/rest/openapi.json.