Track/Channel White Lines?

Can someone help satisfy my curiosity on this? I’ve always seen them but never really understood what the little “White Line” means on a Project Track or Mixer Channel. They appear to the right of a Track number and above a Mixer Channel number.

The only thing I’ve noticed is that if I am using more than one Project Track and/or Mixer Channel visibility configs the White Lines indicate differences between Project and Mixer configs (but even this is not very consistent…).

The attached Pic has a Project Track view with red highlights around the tracks with White Lines.

Thanks!
CB9_Track(WhiteLines).PNG

The channels are selected / controlled by a remote control device.