Part 4, Chapter 4, Section 3 of the "Patent Examination Guidelines" stipulates very clearly:
The receipt of the oral hearing notice for the invalidation procedure or the reexamination procedure should contain the name of the party concerned. Sign or stamp. If a person expresses his/her participation in the oral hearing, the name of the person participating in the oral hearing shall be stated. If a witness who has been appointed to give testimony is required to appear in court to testify about his or her testimony, a statement should be made in the receipt of the oral hearing notice, and the witness's name, work unit (or occupation) and the facts to be proved should be stated.
The number of each party and its attorneys participating in the oral hearing shall not exceed four. If the number of persons participating in the oral hearing stated in the receipt is less than four, other persons may be designated to participate in the oral hearing before the oral hearing begins. If multiple persons from a party participate in the oral hearing, one of them shall be designated as the first spokesperson to make the main speech.
If the party concerned is unable to attend the oral hearing on the designated date, he or she may entrust his or her patent agent or other person to represent him in court.
If the party entrusts a patent agency to act in accordance with Article 19 of the Patent Law, the agency shall appoint a patent agent to participate in the oral hearing.