code: public static void setPreferredAttributeValueForRoadType(RoadType type, String value) {
  		final Preferences prefs = Preferences.userNodeForPackage(RoadNetworkConstants.class);
  		if (prefs != null) {
  			final String sysDef = getSystemDefault(type);
  			if (value == null || "".equals(value) || sysDef.equalsIgnoreCase(value)) { //$NON-NLS-1$
  				prefs.remove("ROAD_TYPE_VALUE_" + type.name()); //$NON-NLS-1$
  			} else {
  				prefs.put("ROAD_TYPE_VALUE_" + type.name(), value); //$NON-NLS-1$
  			}
  		}
  	}
docs: Set the preferred value of road type
  used in the attributes for the types of the roads.
  
  @param type a type
  @param value is the preferred name for the types of the roads.