Hover any box to open its explanation — the boxes marked ▶ have a video. Click to keep the panel open while you watch. Drag the ◇ grips or use + / − to add and remove heads and blocks, and click a ✚ to delete a residual connection.

Tap any box for its explanation — the boxes marked ▶ have a video. Use + / − to add and remove heads and blocks, and tap a ✚ to delete a residual connection. Pinch or use the zoom buttons to read the labels.