The revalidation of the certificate will be mandatory by means of continuing education credits. The NMC has committed to developing and implementing a system of revalidation. It is most frequently required for appraisal, revalidation and continuing professional development. No unlicensed but registered doctor in the UK is subject to revalidation. Revalidation will be introduced from April 2016. Revalidation was eventually implemented in late 2012. Recent revalidation of the species "Mammuthus rumanus" influences several interrelated aspects of mammoth evolution. Revalidation is scheduled to start in 2012.