Specifies the amount of vertical space between horizontal gridlines.
This element contains a value that sets the vertical distance between gridlines in points. If this element is not specified, the vertical space between gridlines 9.35 pt, the default value.
DisplayHorizontalDrawingGridEvery, DisplayVerticalDrawingGridEvery, DrawingGridHorizontalOrigin, DrawingGridHorizontalSpacing, DrawingGridVerticalOrigin, UseMarginsForDrawingGridOrigin
See the example in the DisplayVerticalDrawingGridEvery element topic.