Interface FlowOptions

The columns the chart drew its nodes in, left to right, each naming its nodes top to bottom as FlowPoint.source and target name them.

Without it MAIDR derives the columns: a node sits one column past the furthest node feeding it, and a column is in the order the flows first name its nodes. A library that lays its nodes out otherwise -- d3-sankey's justify alignment, which Mermaid draws with, puts every sink in the last column, and its relaxation reorders each column -- declares where it drew them, so that Up and Down, the stereo position, the braille rows and the object list's stages follow the drawing.

Used only when it names every node exactly once and every flow runs from one column to a later one; otherwise the columns are derived. A chord diagram, which cycles, has no columns to declare.