use size=50;
cell a {
    box a;
    below rightof box b;
    use line.width=0.5;
    (a@80%, a@top)++(b@right+10,);
    mark -10 [marker.type=solid, marker.ymul=0.5];
    (b@right,b@20%)++(, a@top-10);
    mark -10 [marker.type=solid, marker.ymul=0.5];
    text: \-(a@top, b@right) [bottom=a@top+33, left=b@right];
}
space 50;
cell b {
    use size=50;
    box a;
    below rightof box b;
    use line.width=0.5;
    (a@80%, a@top)..(b@right+5,);
    (b@right,b@20%)..(, a@top-5);
    (a@180%, a@top-10)++(b@right+10,);
    mark -5 [marker.type=solid, marker.ymul=0.5];
    (b@right+5,b@-80%)++(, a@top-15);
    mark -5 [marker.type=solid, marker.ymul=0.5];
    text: \-(a@top-10, b@right+5) [bottom=a@top+23, left=b@right+5];
}
bye;
box A; box B; box C;

(A@middle, A@bottom)->(C@middle, C@bottom) [
    via=(A@middle, A@bottom+10), 
    via=(C@middle, C@bottom+10)
];  
