Why did Chengdu Railway Bureau mention three books?

Hello, what are the three books of Chengdu Railway Bureau? The "three-position promotion" of Chengdu Railway Bureau refers to the employee promotion system introduced by the Railway Bureau for the three positions of some employees (that is, professional and technical personnel, administrative personnel and workers). Specifically, the three-part system requires employees to have higher professional knowledge and skills in the corresponding fields, accumulate certain work experience, and meet the promotion conditions. After passing the examination and evaluation, you can get the corresponding professional title promotion and salary increase, and you can further serve as a higher level and more complicated task. Three-oriented training is an important way for Chengdu Railway Bureau to implement the talent training plan, which aims to motivate employees to exert their professional skills and management experience and promote the sustained and high-quality development of enterprises.