This system is formulated to ensure the effective performance of the contract, safeguard the legitimate interests of the company, standardize the project visa behavior, ensure the authenticity, timeliness, rationality and accuracy of the visa, achieve "prior control, process supervision, and timely treatment after the event", and effectively control the project cost. Project visa refers to the situation that is inconsistent with the conditions specified in the bidding documents and the construction contract, resulting in project cost