This D3.js (v5) example demonstrates how to reorder a categorical axis by dragging its labels. It displays a draggable list of four Iris flower feature names (sepal length, sepal width, petal length, petal width) in a fixed-position panel. Users can drag and drop each item to change its position, which updates the underlying `axis` array. The implementation uses native HTML5 drag-and-drop events (`dragstart`, `dragover`, `drop`) and DOM manipulation to swap list items, providing a simple interface for interactive axis reordering.