Specifies how data source contents are sorted by default, when sort order is not specified by the bound control.
A String object which contains the names of the columns against which data source contents are sorted.
This property accepts a string containing a column name followed by the sort order - "ASC" (ascending) or "DESC" (descending).
Columns are sorted ascending by default - "ASC" can be omitted.
Multiple columns can be separated by semicolons.