##Influence arrow route
##via routing arrow
##Use the 'via' attribute (multiple times if needed) to specify a block's side, where the arrow shall be routed. The arrow will be as short as possible while fulfilling the 'via' constraints.
col c1 {
    row {
        box A;
        below box B;
        box C [top=A];
    }
    B->C [via=A@topleft, 
          line.color=red];
    use margin=0;
    text: via A@topleft;
}
below 20 col c2 {
    row {
        box A;
        below box B;
        box C [top=A];
    }
    B->C [via=A@right, 
          line.color=red];
    use margin=0;
    text: via A@right;
}