Chart Type for Flow / Process Data. Keywords: flow, process, sankey, distribution, source, target, transfer. Best Chart: Sankey Diagram. Secondary Options: Alluvial, Chord Diagram. When to Use: Showing how quantities flow between nodes; multi-source multi-target distribution. When NOT to Use: Flow directions form loops (use network graph); fewer than 3 source-target pairs; mobile-primary context. Data Volume Threshold: <50 flows: SVG; ≥50: Canvas; >200 flows: aggregate minor flows into 'Other' node. Color Guidance: Gradient from source to target color. Flow opacity: 0.4–0.6. Node labels always visible. Accessibility: C — Structural flow charts cannot be conveyed by color alone. Provide flow table. Avoid on mobile.. A11y Fallback: Flow table (Source → Target → Value); keyboard-traversable node list with tab stops. Library: D3.js (d3-sankey), Plotly. Interactive Level: Hover + Drilldown.