i'd also look at whether the attributes could be modeled as relations, not as individual things hanging off of a resource, but as their own definitions, e.g.:

definition user {}

definition organization {
  relation user: user
  permission member = user
}

definition region {
  relation user: user
  permission view_region = user
}

definition resource {
  relation user: user
  relation organization: organization
  relation region: region
  permission view = user + organization->member + region->view_region
}

that kind of thing