AUTO Mode Enhancements
AUTO mode determines the shape of returned XML, based on the query. In determining how elements are to be nested, AUTO mode heuristics compare column values in adjacent rows.
In SQL Server 2000, the columns of all types, except ntext, text, and image, were compared. In SQL Server 2005, columns of xml type are also not compared, but columns of type (n)varchar(max) and varbinary(max) are compared. Also, for SQL Server 2005, derived table support has been improved so that it can be used to group under the same element columns from different tables, but hide the join from AUTO mode heuristics.