DataSet.WriteXML is difference between .NET 1.1 and .NET 2.0?

I have old program written in .NET 1.1 which output a XML file similar as :

<?xml version="1.0" standalone="yes"?>
<EDIDatasSet xmlns="http://tempuri.org/EDIDatasSet.xsd">
<Booking ID="xxx" LastUpDate="2006-11-29T16:20:16.7170000+08:00"
................. >
<Detail ID="xxx" Reference="xxxx" STYLE="" REMARK="" />
</Booking>

When I changed to .NET 2.0, it became to:

<EDIDatasSet xmlns="http://tempuri.org/EDIDatasSet.xsd">
<Booking>
<ID>xxx</ID>
<LastUpDate>2006-11-29T16:20:16.7170000+08:00</LastUpDate>
..........
</Booking>
<Detail>
<ID>xxx</ID>
<Reference>xxxx</Reference>
<STYLE></STYLE>
<REMARK></REMARK>

</Detail>

It make xml file too large!! and the relationship between booking and detail
table like missed, How should I do?