Slitherine

I am fairly new to Order of battle so forgive me for what I'm sure is a newby and obvious question to some...but here goes.

Once in a while one of the units I have has half of it's country icon be red and or not whole....what does this mean?

It seems my unit is still in supply so I don't think it's that...

See attached pic for an example.

I think it means it has moved. But I am not that sure, to be honest. Shame on me. I only check the efficiency indicator.

Moved, but may still attack if I remember correctly.

Moved, but may still attack if I remember correctly.

Correct. If you zoom in closer you should be able to see that the right half of the roundel has (half of a) red crosshair icon in it.

There is also a version where the left is dark with a green arrow in it, meaning "has attacked but can still move". I can't remember if any unit or situation actually allows that to appear in the game however.