The tag allows dynamic columns functionality in a rich:dataTable. It is used like a UIData component which iterates through a data model to create columns.

The component uses a standard value/var pair of attributes to provide binding to data model and request scoped variable for iteration through this data model.

The next simple example shows you a simple use-case where ten types of cars are created and a list of models with prices is generated for each type of car. In the dataTable cars are grouped by type in a separate columns.

DataTable Columns example

Additionally as you see could be added to this component in the same way as for simple rich:column.

In this example every column provides sorting by car prices