From the company Q&A on pfc web site
Q: If enough people do not bid for CDG/HKG, how will the inverse assignments work?
A: Inversing pilots permanently into an FDA is not allowed by the CBA. If the vacancies are not bid by crewmembers on the property, then new hires would be the only option available, short of canceling the FDA. The SVT option was established for flexibility so that if crewmembers exit training late (training problems, simulator problems, etc.), if the aircraft arrive early (right!), or aircraft utilization is increased initially, we could still man the flight schedule. However, long term relief by use of the SVT program is not an acceptable option.