Adds the sort field (expression parameter) if the collection does not alreqady contain the field. Else the sort order of the field will be inverted. The default change order is Asc -> Desc -> No Sort. The No-Sort state can be controlled using AllowNaturalSort property

public void ChangeSortOrder(
	string expression
)

Public Sub ChangeSortOrder ( 
	expression As String
)

public:
void ChangeSortOrder(
	String^ expression
)

member ChangeSortOrder : 
        expression : string -> unit