The meaning is according to the AutoscrollSizeUnit property (the multiple of the page size, the time in seconds, the shortest period, ...).
The time of scrolling or if to scroll at all, is given by setting the AutoscrollType property.
It is scrolled only if the Autoscroll property is set to true.
var oTView = pMe.Items("../TrendView");
var nAutoSize = oTView.AutoscrollSize; //reading
oTView.AutoscrollSize = 0.2; //writing