[CE C#] How to set dimension unit.

 Hello All,

I can place dimension in MS, but the value is always metric, I'd like to know how to place imperial dimension. I have tried the following codes(I tried them by each row, not all the codes together)

            UnitDefinition MyUnit= new UnitDefinition(  UnitBase.None  , UnitSystem.English ,35,45,"MyUnit");
            dimStyle.SetUnitsProp(MyUnit, MyUnit, DimStyleProp.Value_Unit_UNITS);
            dimStyle.SetOneUnitProp(MyUnit, DimStyleProp.Value_UnitMaster_ONEUNIT);
            dimStyle.SetOneUnitProp(MyUnit, DimStyleProp.Value_UnitSub_ONEUNIT );
            StatusInt  mytest= dimStyle.SetUnitsProp(UnitDefinition.GetStandardUnit(Bentley.DgnPlatformNET.StandardUnit.EnglishFeet), UnitDefinition.GetStandardUnit(Bentley.DgnPlatformNET.StandardUnit.EnglishInches), DimStyleProp.Value_Unit_UNITS);

I checked the value of MyUnit, it is inch already, but it is the metric value placed still. Anyone can tell me how to place imperial dimension(the file unit is metric)? Thanks a lot. 

Also how to set the accurracy for imperial dimension, for example, 0.001 and 1/16".