# ExtLocUnion

Location: [gRPC API](https://developer.m-files.com/APIs/gRPC-API/index.md) > [Reference](https://developer.m-files.com/APIs/gRPC-API/Reference/index.md) > [Messages](https://developer.m-files.com/APIs/gRPC-API/Reference/Messages/index.md)

HTML version: https://developer.m-files.com/APIs/gRPC-API/Reference/Messages/MFiles.ExtLocUnion/

Union for extloc type specific data in ExternalLocation.

- **Full name:** `MFiles.ExtLocUnion`
- **Proto file:** [`mfiles/structs.proto`](https://developer.m-files.com/APIs/gRPC-API/downloads/proto/mfiles/structs.proto)

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## Fields

| Field | Type | Number | Description |
|---|---|---|---|
| <a id="f-file_source"></a>`file_source` | [`FileSource`](https://developer.m-files.com/APIs/gRPC-API/Reference/Messages/MFiles.FileSource/index.md) (oneof data) | 1 | File source definition. |
| <a id="f-mail_source"></a>`mail_source` | [`MailSource`](https://developer.m-files.com/APIs/gRPC-API/Reference/Messages/MFiles.MailSource/index.md) (oneof data) | 2 | Mail source definition. |

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## Used in fields

- [`ExternalLocation.data`](https://developer.m-files.com/APIs/gRPC-API/Reference/Messages/MFiles.ExternalLocation/index.md#f-data): The type-specific data as a union.