Is it possible to have arrows to show flow in both directions?
As in an equalizer line or crossover line?
my understanding is that if no flow arrow is present then the flow is assumed to be able to go both ways
but to answer your question...the flow arrows are placed manually and the direction can be controled with the blue triangle grip when selected, so i dont see why you couldnt actually place them (even though this is not ussually considered normal practice.
I am running 2012 & arrows are directional to the direction you generate the line. But you can pick the line then right click for OSM & select "schematic Line Edit" then "Reverse Flow". As I now notice, I can manually place an arrow & then "rotate it to get the 2 bi-directional arrows.