Question: Permissions has role_id

[fnoquiq]

Why in the permissions is there a role_id if it already contains the user_id?
The role_id should be connected to the user, right? A user should only have a relationship for a single role

Permission {
  user_id: 1,
  role_id: 2,
  resource_id: 3,
  create: true,
  update: true,
  read: true,
  delete: true
}