Clarification needed on the following command

Need some clarification on the private endpoint creation. The documentation below suggesting that you can use an existing subnet in other resource group or subscription for the Private Endpoint deployment. But when attempted, it's throwing error.

Please review and clarify if this is intended to be working or not.

--subnet
Name or ID of an existing subnet. If name specified, also specify --vnet-name. **If you want to use an existing subnet in other resource group or subscription,** please provide the ID instead of the name of the subnet and do not specify the --vnet-name.

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#### Document Details

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* ID: 8911e94f-9496-a68d-50c0-b5d536a375a4
* Version Independent ID: cc37b77b-0fa2-991b-e16b-fcdbbf183853
* Content: [az network private-endpoint](https://docs.microsoft.com/en-us/cli/azure/network/private-endpoint?view=azure-cli-latest#az_network_private_endpoint_create)
* Content Source: [latest/docs-ref-autogen/network/private-endpoint.yml](https://github.com/MicrosoftDocs/azure-docs-cli/blob/master/latest/docs-ref-autogen/network/private-endpoint.yml)
* Service: **virtual-network**
* GitHub Login: @rloutlaw
* Microsoft Alias: **routlaw**