Variety Testing concerning Plant Breeders’ Rights and/or listing on the National list and drafting of variety descriptions is based on UPOV guidelines and CPVO protocols. Naktuinbouw has developed calibration books for a large number of crops. The calibration book is a practical manual that provides an illustrated explanation for each plant characteristic. Calibration books are available for several crops. The list of calibration books can be found on the Dutch page of this website.