There are three selectable modes in RadGrid control. These modes could be manipulated using the SelectableMode property. SelectableMode is a GridItem enum property which determines if the item could be selected on the server, the client or both. Here is description of the possible modes:
SelectableMode.ServerAndClientSide: This is the default value and it represents the current selection behavior depending on the prefered selecting mechanism.
SelectableMode.ServerSide:This value allows the developer to select items on the server which could not be changed by the end user.
SelectableMode.None: The item could not be selected on the client or the server. If the GridItem.Selected value have been true it is automatically deselected when SelectableMode is set to None.