### Username for external authentication

When a user is authenticated by some service external to the site, this field contains the identifier for the user on the remote service. It is possible for a user to have several remote usernames stored in Mahara, but each one must be associated with a different external authentication method.

The current rules for the update of this field are as follows:

- If you wipe the contents of this field and submit your changes, any external username associated with this user and the selected authentication method will be deleted.
- If you update the contents of this field to anything other than the default, the external username will be reset, or a new one will be created if it doesn't exist yet.
- If you leave the contents of this field on the default and submit, a new external username will be created if one doesn't exist yet. However, if the user already has an external username for the selected authentication method, and it is different to the default, it will not be overwritten.