The technical training network has automated books. Ji Cheng Training Network is an automatic training institution with 15 years of teaching experience, with more than 4 million students and more than 640 courses, including electrical basics, PLC, frequency converter, servo, man-machine interface, mechanical drawing, numerical control and robotics. In addition, book classification, also called book classification thesaurus, is classified according to the contents, forms, genres and readers' usage. Under the guidance of certain philosophical thoughts, the books of various disciplines are divided into several categories according to their subject contents by using the principle of knowledge classification and logical methods. Each category is divided into many subclasses, and each subclass is divided into molecular subclasses.