Useful. Guo Tong Certification Technology Training Center is one of the four institutions approved by CNCA with the qualification of training national registered auditors of food safety management system. With the technical training certificate certified by Guo Tong, you will have broader opportunities and development space in job hunting and promotion. Guo Tong certification technical training certificate means that students who pass the training examination will obtain the qualification certificates of ISO22000 food safety management system internal auditor and ISO900 1 quality management system internal auditor issued by CCST within one month.