Maps group versus user
| Column | Type | References | Comments |
| id | Integer | Primary key | |
| vdb_id | Integer | ||
| discriminator | Integer | Indicates what this record is for. For example, 56 is Workflow App, 17 is Project, 61 is group, 58 is Custom Report | |
| role_id | Integer | db_group.id | ID of the role played by user |
| user_id | Integer | db_person.id | ID of the user |
| workspace_id | Integer | db_group.id | ID of group if group membership. Null otherwise |
| project_id | Integer | db_project.id | ID of project if project membership. Null otherwise |
| report_id | Integer | db_custom_report.id | ID of report if report/client membership record. Null otherwise |