The first is that the first-class supplier's network access certificate (the network access product is PetroChina's first-class material) is directly managed by ministry of materials and equipment, the material of PetroChina headquarters;

The second type is that the second-level supplier's network access certificate (all materials except the first-level materials) is managed by the regional company to which PetroChina belongs, and the certification management is implemented. The supplier's qualification can be filed at the headquarters.