Cinema 4D Program Documentation Reference Cinema 4D Basic Features Select Menu
Function available in CINEMA 4D Prime, Visualize, Broadcast, Studio & BodyPaint 3D

Fill Selection

In edge mode, Fill Selection creates a polygon selection from an existing edge selection (preferably closed). Move the mouse pointer over the edge selection. When the polygons for the selection change color, click to select those polygons — polygon mode will be activated automatically.

Creating a polygon selection from a closed edge selection using Fill Selection.