Store columns order of WPF DataGrid.

Question

I developing WPF Application. Also I use WPF DataGrid in my app. I store columns visibility in XML file like

<ColumnSysName Visible="true" />

I want also to store columns order in the same file like

<ColumnSysName Visible="false" OrderIndexInDataGrid="3"/>

How can I do this? Or Maybe you have your technics how to store order for WPF DataGrid. Thank for help.