Thanks Again Bonnie for your reply, your solution make sense but i would have to cut and paste the method FillWithXML to all the derived classes where if the generated DS would already derive from my base class, i would not have to code anything other then the very specifics of that class.

Is there any way to have multiple inheritance in C# ? like this:

public class Ar_CustMaster_DataSet : MyNameSpace.MyDataSet, IMyDataSet

>Stephane,
>
>Put public methods/properties in your base DataClass that you call from your sub-classed DataSets. Something like this:
>

>	public interface IDataSet
>	{
>		void FillWithXml(string XML);
>	}
>
>	public class XmlConverter
>	{
>		public void ImportXml(DataSet Data, string XML)
>		{
>			StringReader sr = new StringReader(XML);
>			Data.ReadXml(sr, XmlReadMode.InferSchema);
>			Data.AcceptChanges();
>		}
>	}
>

>Then in your sub-classed DataSets:
>

>public class Ar_CustMaster_DataSet : Ar_CustMaster, IMyDataSet
>{
>  private MyBaseDataClass.XmlConverter Converter = new MyBaseDataClass.XmlConverter();
>
>  public void FillWithXML(string XML)
>  {
>    this.Converter.ImportXML(this, XML);
>  }
>}
>

>
>~~Bonnie
>
>
>
>
>>Thanks Bonnie,
>>
>>That's what i did but the problem with interface is i have to cut & paste the implementaion code to all my derived dataSets since the code is the same for all. It would be much easier to simple derive from a base class containing all the common code. Looks like nothing is easy in .NET!!
>>
>>
>>>Stephane,
>>>
>>>You don't want to mess with the generated code. I recommend using an Interface and then create a sub-class from your typed DataSet. Something like this:
>>>

>>>public interface IMyDataSet
>>>{
>>>  void MyDataSetMethod();
>>>}
>>>public class Ar_CustMaster_DataSet : Ar_CustMaster, IMyDataSet
>>>{
>>>  public void MyDataSetMethod()
>>>  {
>>>    // whatever code
>>>  }
>>>}
>>>

>>>
>>>~~Bonnie
>>>
>>>
>>>>I am trying to figure out how i can make the generated typed datasets from VS 2003 us my dataSet base class instead of the Syste,.Data.DataSet base class.
>>>>
>>>>The genarated code produce this:
>>>>

>>>>    public class AR_CustMaster : DataSet {}
>>>>

>>>>
>>>>I need the dataset generator to produce this:
>>>>

>>>>    public class AR_CustMaster : MyDataSet {}
>>>>

>>>>
>>>>I know i can go in the generated .cs file and manually change it but as soon as the dataset is regenerated, my changes are lost.
>>>>
>>>>Is there any way to make the change permanent ?
>>>>
>>>>Thanks.