The authoritative appraisal certificate should be marked with the words "CMA", "CML" and "CNAL". There must be at least one of the three signs, and all three signs indicate that the appraisal institution has the highest ability and level.

CMA-the basic requirement of national laws for testing and inspection institutions, and the institutions with this mark are statutory inspection institutions;

CAL- is the symbol of the inspection organization recognized by the national quality inspection. Institutions with this mark are qualified to make arbitration inspection conclusions. Compared with the mechanism with CMA only, the mechanism with CAL has better quality and reliability.

Cnal-the symbol of national laboratory. According to the relevant agreements of China's accession to the WTO, the "CNAL" logo can be recognized internationally, such as the United States, Japan, France, Germany, Britain and other countries.