anchor.diff:          case "class":
             result.Class = attributeValue;
             break;
  -        case "playOrder":
  +        case "playorder":
             result.PlayOrder = attributeValue;
             break;
         }
  
positive.code:               readNavigationLabel(navigationListChildNode);
            result.NavigationLabels.add(navigationLabel);
            break;
          case "navTarget":
            EpubNavigationTarget navigationTarget =
                readNavigationTarget(navigationListChildNode);
            result.NavigationTargets.add(navigationTarget);
  
negative.code:         case "class":
            result.Class = attributeValue;
            break;
          case "playorder":
            result.PlayOrder = attributeValue;
            break;
        }
  