See http://marketplace.sitecore.net/en/Modules/Add_Device_Layout_Wizard.aspx for more information.
When creating a site it's common for many nodes to diverge their layout from their template's Standard Values. Since the layout field encapsulates all devices, once that link is broken it can be a...
1.Add Data Row Range.
2.Remove Data Row Select.
3.Group By Aggregation (Sum,Count,Avg, Max, Min).
4.DataTable to XML Document.
5.DataTable to XML File.
6.Sum,Count,Avg, Max, Min.