This method returns the DataSet which would have been used for a Get or Move method. Request level is set and UIDs are set according to the value of the level. If Patient Level then PatientID is set; if Study Level then PatientID and StudyUID are set; if Series Level then then PatientID, StudyUID and SeriesUID are set; if Image Level then PatientID, StudyUID, SeriesUID and InstanceUID are set.