Request that the NETCONF server lock the candidate
configuration, enabling the client application both to read and change
it, but preventing any other users or applications from changing it.
The client application must emit the
<unlock/> tag to unlock the configuration.
If the NETCONF session ends or the application emits the
<unlock> tag element before the candidate configuration
is committed, all changes made to the candidate are discarded.
<target> tag element
and its contents are explained separately.