How are ‘Co-Researchers’ in a ‘Researcher Details’ page related to the researcher?

‘Co-Researchers’ are the research project’s ‘Principal Investigator’, ‘Co-Investigator (Kenkyū-buntansha)’, ‘Co-Investigator (Renkei-kenkyūsha)’, and ‘Research Collaborator’, who are listed in ‘List of Research Projects’ on the researcher’s details page.