For example; hold Plate and Pipe then take a Node (3.8) or Nozzle (3.9) supplementary exam and pass. All 3 categories revalidates for 5 years.
If you hold PCN Ultrasonic Welds Level 2, you conduct and pass a supplementary examination of a Weld category that you don't currently hold, it will re-validate your existing certification for another 5 years.