Planar Confluent Orthogonal Drawings of 4-Modal Digraphs

In a of directed graph (digraph) vertices are drawn as points in the plane and edges orthogonal polylines starting with vertical segment ending horizontal segment. Edges may overlap their first or last segment, but must not intersect otherwise. PCODs can be seen variant Kandinsky drawings planar L-drawings subdivisions digraphs. The maximum number subdivision an edge is then . A PCOD if each monotonically increasing y-coordinates no starts decreasing y-coordinates. We study split complexity (quasi-)upward for various classes graphs.