  We point out two flaws in the algorithm of Brandes and K\"opf (Proc. GD
2001), which is often used for the horizontal coordinate assignment in
Sugiyama's framework for layered layouts. One of them has been noted and fixed
multiple times, the other has not been documented before and requires a
non-trivial adaptation. On the bright side, neither running time nor extensions
of the algorithm are affected adversely.

Data Structures and Algorithms