Reference samples. in which artificial discontinuities (defects) are fabricated. are used to verify non-destructive testing procedures. Artificial discontinuities are known defects of reference samples and enable verification the possibilities of using the chosen NDT method for the identification of location and depth of discontinuities. https://www.hindigyanvishv.com/super-find-Red-Pygmy-reg-Dogwood-Tree-limited-super/