It means they have no device to control - they are homeless, so to speak. If you had one or more XYPad/Repeater/Hydra devices in your song, you’d be able to target them using prev/next buttons, and press “lock” to take control.
Please check out the documentation for each application
http://forum.renoise…8-duplex-xypad/
http://forum.renoise…uplex-repeater/