IIRC something simple like, "Combine units".
Edit: Also, if you can combine the units, the button is active (lit-up), and you don't get the TOE info.
BTW it's nice if when posting an illustration, that you cut off the '
fat' first so that people with limited band-width don't have to download the entire full-screen screenshot when only a section is important or interesting; eg.:
only this
or this if you need the unit info
