Similarities between individuals or groups of individuals taught the same or similar writing systems are known as Class Characteristics. These may be quite different from other groups of individuals but consistent within that specific group.
Class characteristics may serve to narrow down the search when comparing a questioned writing to several different writers’ standards but they will not provide a proper basis for a definitive identification. However, lack of common class characteristics can provide for a disassociation of the writer from the questioned material. Simply put, class characteristics may identify a species, but not an individual.