1. Use original work unit: you can fill in the work unit before retirement, and mark "retired" or use similar words after the name of the unit to accurately reflect its past professional identity.
2. Fill in "None" or "Freelance Researcher": If the retired doctoral supervisor has not joined other organizations or institutions, he can fill in "None" or "Freelance Researcher" in the column of work unit to indicate that he does not belong to any specific work unit at present.
3. Fill in relevant part-time or honorary positions: Retired doctoral supervisors will continue to hold part-time or honorary positions, such as visiting professors and consultants. You can fill in the corresponding work information in the column of work unit to show their current academic activities.