> ## Documentation Index
> Fetch the complete documentation index at: https://docs.e6data.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Addresses and access

> Use the HTTP address and API prefix of the instance you intend to operate. The native engine routes use /api/v1. An embedded deployment can mount Unified under another prefix, such

How-to guideApplies to: Unified engine deployments

Use the HTTP address and API prefix of the instance you intend to operate. The native engine routes use `/api/v1`. An embedded deployment can mount Unified under another prefix, such as `/api/v1/unified`.

## Select the connected instance

Use your engine's HTTP origin and API prefix in your client. The OpenAPI document uses native paths. Account for any deployment-specific prefix when importing it into another client.

## Understand the access context

The native HTTP API uses its configured owner for engine requests. The owner is not a field a caller can override in each body. A platform or gateway can apply its own login and access rules before requests reach Unified.

Do not assume that a bearer token is required or supported by every native deployment. Use the access mechanism configured by your host or gateway.

For a gateway that needs an Authorization header, add it to the copied code in your own client. Keep API credentials in your client configuration.

## Browser restrictions

A different-origin engine must permit the browser's request through its CORS policy. Your client must follow the deployment's access controls. Browser-managed headers such as Cookie and Host cannot be set freely from JavaScript.

A network failure can mean an unreachable address, a browser policy, a missing login, or a lost response. Inspect network and server evidence before changing a mutation's identity.

## Use resource revisions

Read the current resource before updating it. Requests use fields such as `expected_revision` or catalog `revision` to reject stale changes. Request identity and revision checks have different purposes; see [Request identity](https://docs.e6data.com/transformation/http/request-identity.md).


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