A NC or nonconformity is where a test or calibration does not
conform to planned arrangements as per the ISO 17025 Standard. A
CAR or Corrective Action Request is a formal methodology for
documenting a nonconformity and includes identification, root cause
analysis, action taken to prevent recurrence and review of action
taken to assure effectiveness. The CAR process is similar in ISO
9001, ISO 13485, etc.