Vyatta NOS keeps two versions of the configuration current — candidate and running.

You can also think of these as the 'uncommitted' and 'committed' configuration, respectively.

Running/committed configuration

This is the configuration that is currently in use with the live system.

Candidate/uncommitted configuration

By default, this is simply a copy of the running configuration — until you modify it. You can modify it as much as you like to draft changes that you might commit to the running configuration.