private String descDuty(Actor a) {
    final Background v = a.vocation() ;
    final String VN = v == null ? a.species().toString() : v.nameFor(a) ;
    if (a.mind.home() == this) return "(Resident "+VN+")" ;
    if (a.mind.work() != this) return "(Visiting "+VN+")" ;
    final String duty = personnel.onShift(a) ? "On-Duty" : "Off-Duty" ;
    return "("+duty+" "+VN+")" ;
  }