1. Secret sign: used to identify the most sensitive information, which can only be shared and accessed by specific authorized personnel, including financial data, business plans, customer data, etc. The secret sign is red, round or square with the word "secret".
2. Internal use mark: used to identify information used only within the company and not shared with external personnel. This information includes internal documents, training materials, employee data, etc. The internal use sign is yellow, triangular or rectangular with the words "internal use".
3. Restricted sign: used to identify restricted information, which can only be enjoyed and accessed under certain conditions, including contracts, legal documents, partner data, etc. The restriction sign is blue and can be hexagonal or trapezoidal in shape, with the word "restriction".