Creates a new rowset in the data source for some parent key.
Returns the associated Rowset object.
The possible values for the required parent-key are described in topic: dsc.rowSet() function.
NOTE 1: If parent-key has the value 'current', then no Rowset object is created, and the currently active Rowset is returned.
NOTE 2: if the Rowset to be created already exists, then no new Rowset is created.