+-----+  +-----+  +-----+  +-----+
        | AT1 |  | AT2 |  | AT3 |  | AT4 |
        +-----+  +-----+  +-----+  +-----+
          ^         ^        ^        ^
          |         |        |        |
          |      +-----+     |        |
          +------| Re1 |----+|        |
          |      +-----+              |
          |         ^                 |
          |         |                 |
          |      +----+   +----+      |
          +------|Re2 |   |Re3 |------+
                 +----+   +----+
                   ^          ^
                   |          |
                   | +------+ |
                   +-| stub |-+
                     +------+