What does CPC mean when applying for patent electronically on the website of the State Intellectual Property Office? What is the full English name?

Well, this is a client for electronic applications currently in use. Users can edit documents in it and upload them to the patent office. They don’t have to prepare paper documents and submit them to the patent office. But before using You need to register as an electronic user, but I have to complain, this thing is really difficult to use and it’s rubbish. . .