188.8.131.52.3.2 Order By Format
An example of an OrderBy clause is as follows.
<OrderBy > <FieldRef Name='ID'> </FieldRef> <FieldRef Name='Title' Ascending='False'> </FieldRef> </OrderBy>
The OrderBy clause contains a FieldRef element which MUST refer to a valid field name. Valid field names are provided in the Name attribute of the _sProperty element (see section 184.108.40.206.3.3) returned from the GetList operation. The Ascending attribute is optional and indicates ascending order if value is true, descending otherwise. By default, Ascending is true.