What audit systems need to be formulated within the enterprise?

I personally think that the internal audit system and regulations formulated by the internal audit department can be divided into the following three levels:

1. The programmatic system of company internal audit can have many names, such as internal audit system and internal audit charter. ...

2. Internal control system audit system, economic responsibility audit system, financial audit system and other sub-audit systems, regulations or rules.

3. Internal management system of the department, such as audit review system, working paper preparation method, on-site work guide, etc.