Configure Order By Expression - LinqDataSource
The Configure Order By Expression dialog box enables you to define how the data from the LinqDataSource control is sorted. You can specify up to three properties that will be used to sort the results. For more information about how to sort the data from a LinqDataSource control, see the OrderBy property.
You access this dialog box by clicking Order By in the Configure Data Source - LinqDataSource dialog box when the AutoGenerateOrderByClause property is false. If you set the AutoGenerateOrderByClause property to true, the Order By button displays the Expression Editor dialog box. This is because you cannot set the Order By clause and also have the LinqDataSource control automatically create the Order By clause.