enum style_t { allow_long =  1, allow_short =  allow_long << 1, allow_dash_for_short =  allow_short << 1, 
               allow_slash_for_short =  allow_dash_for_short << 1, long_allow_adjacent =  allow_slash_for_short << 1, long_allow_next =  long_allow_adjacent << 1, 
               short_allow_adjacent =  long_allow_next << 1, short_allow_next =  short_allow_adjacent << 1, allow_sticky =  short_allow_next << 1, 
               allow_guessing =  allow_sticky << 1, case_insensitive =  allow_guessing << 1, allow_long_disguise =  case_insensitive << 1, 
               unix_style =  (allow_short | short_allow_adjacent | short_allow_next
                      | allow_long | long_allow_adjacent | long_allow_next
                      | allow_sticky | allow_guessing 
                      | allow_dash_for_short), default_style =  unix_style };