void setMonitor(int cmdPt) throws ScriptException {
		// on off here incompatible with "monitor on/off" so this is just a SET option.
		// cmdPt will be 2 here.
		boolean showMeasurementNumbers = false;
		checkLength3();
		switch (statement[cmdPt].tok) {
		case Token.on:
			showMeasurementNumbers = true;
		case Token.off:
			viewer.setShapeProperty(JmolConstants.SHAPE_MEASURES, "showMeasurementNumbers",
					showMeasurementNumbers ? Boolean.TRUE : Boolean.FALSE);
			return;
		case Token.identifier:
			if (!viewer.setMeasureDistanceUnits((String) statement[cmdPt].value))
				unrecognizedSetParameter();
			return;
		}
		viewer.setShapeSize(JmolConstants.SHAPE_MEASURES, getSetAxesTypeMad(cmdPt));
	}