In order from low to high:

P4-P7: Junior Engineer - Engineer - Senior Engineer - Expert

Currently, fresh graduates generally start at P5, and promotion is decided by voting by professional judges at the two higher levels.

P6-Senior Engineer, the main force of work, generally has more than 3 years of work experience in undergraduate and 1-2 years of work experience in graduate school. Of course, there are also a few outstanding fresh graduates and doctors.

P7-Technical Expert, the main force of work, 5-8 years of work experience in undergraduate and 3-5 years of work experience in graduate school. This was relatively easy to enter before 2015, but with the changes of time, P7 has become the technical end point of a normal person.

P8-Senior Expert, this is difficult to be promoted internally, so P7 has more job hopping.

P9-Senior Expert, they generally lead large teams and have influence on the industry.

P10-Research Institute/Scientist, with a certain degree of fame and influence in the industry, or with many outstanding scientific research achievements. It is really difficult for ordinary people to reach this level.

P11 and above are almost all geniuses, true geniuses.