sort_order - Change default sort order
Usually, displaying data in a list or tree will use the default access key (primary key) defined in the database model for the collection. In order to display a collection with a different sort order, another access key defined for the collection referenced in the data source might be defined. For defining generic sort orders (i.e. indexes referring to generic attributes as language), the generic type may be appended to the sort key name separated by comma (e.g. "title,English").
For control data sources, the sort order value will be ignored, when the control requests column ordering by defining an order column.
When the data source refers to a column, the defined sort order describes the ordering of list items, when a list or tree is ordered by this column (e.g. by clicking the column header).