What are the rules for setting the qualifications of bidders?

① Potential bidders shall not be restricted or excluded under unreasonable conditions. (2) The enterprise qualification grade requirements can only be set according to the minimum qualification conditions required for the project subject to tender. However, if the project is legally marked by lottery, it can be upgraded to a higher level according to the minimum qualification conditions required for the project subject to tender. (3) The qualification grade requirements of the project manager can only be set according to the minimum qualification requirements required for the project subject to tender.