Sorting is supported for parent group break columns only.
For example, if a data set of employees is grouped by department and manager, you can sort the XML data by department. Within each department you can group and sort data by manager. If you know how the data should be sorted in the final report, you specify sorting at data generation time to optimize document generation.
To apply a sort order to a group:
The figure below shows the Properties dialog for the DEPARTMENT_ID element with the Sort Order list displayed.