Revit API創建標高，單位轉換

一業內朋友讓我寫個快速創建標高的插件。
[TransactionAttribute(Autodesk.Revit.Attributes.TransactionMode.Manual)]
  cmdDrawLevel : IExternalCommand
{
     Result Execute(ExternalCommandData commandData,   messages, ElementSet elements)
    {
        UIApplication app = commandData.Application;
        Document doc = app.ActiveUIDocument.Document;
        Selection sel = app.ActiveUIDocument.Selection;
        
        {
            Transaction ts =  Transaction(doc, );
            ts.Start();
                         dStart = RevitTools.Unit.CovertToAPI(.Parse(XmlTools.levelStart), DisplayUnitType.DUT_METERS);
             dDis = RevitTools.Unit.CovertToAPI(.Parse(XmlTools.levelDis), DisplayUnitType.DUT_METERS);
             iNum = .Parse(XmlTools.levelNum);
                        Level levelStart = doc.Create.NewLevel(dStart);
            levelStart.Name = XmlTools.levelPre + ;
                         ( i = ; i <= iNum; i++)
            {
                Level level = doc.Create.NewLevel(dStart + i * dDis);
                level.Name = XmlTools.levelPre + (i + );
            }

            ts.Commit();
        }
         (Exception ex)
        {
            TaskDialog.Show(, );
        }

         Result.Succeeded;
    }
} System;
 System.Collections.Generic;
 System.Linq;
 System.Text;

 RevitCodes
{
     XmlTools
    {
           levelStart = ;
           levelDis = ;
           levelNum = ;
           levelPre = ;
    }
}

 System;
 System.Collections.Generic;
 System.Text;
 Autodesk.Revit.DB;
 System.Configuration;
 System.Reflection;

 RevitTools
{
                  Unit
    {
         Methods
                                                           CovertFromAPI(DisplayUnitType to,  value)
        {
             value *= ImperialDutRatio(to);
        }

                                                           CovertToAPI( value, DisplayUnitType  )
        {
             value /= ImperialDutRatio();
        }

                                                   ImperialDutRatio(DisplayUnitType dut) 
        {
             (dut)
            {
                 DisplayUnitType.DUT_DECIMAL_FEET:  ;
                 DisplayUnitType.DUT_FEET_FRACTIONAL_INCHES:  ;
                 DisplayUnitType.DUT_DECIMAL_INCHES:  ;
                 DisplayUnitType.DUT_FRACTIONAL_INCHES:  ;
                 DisplayUnitType.DUT_METERS:  ;
                 DisplayUnitType.DUT_CENTIMETERS:  ;
                 DisplayUnitType.DUT_MILLIMETERS:  ;
                 DisplayUnitType.DUT_METERS_CENTIMETERS:  ;
                :  ;
            }
        }
        
    }
}url:http://greatverve.cnblogs.com/p/revit-api-create-level.html