Section moves both clipping planes in the same direction by the specified distance, where distance is a real number in the current display units (usually angstroms). This has the effect of displaying a different cross section of the displayed model(s). A positive number displays a cross section closer to the user, while a negative number displays a cross section farther away from the user.
Section moves the clipping planes in the specified manner for the specified number of image update frames (default 1). Commands continue to be processed while the requested motion is in progress. To pause command processing until the motion is finished, use the wait command. To halt an ongoing section, use freeze.