TrendLine object, ReferenceLine object
Sets how trend lines are positioned relative to other chart objects. Trend lines can be layered on top of the chart graphics (or Z axis for 3 D charts), or positioned to the background.
Determines reference line drawing order relative to other chart objects
Read-write, BqDrawingOrder
The DrawingOrder (Property) uses the BqDrawingOrder constant group, which consists of the following constants:
bqDrawingOrderToBack = 2
bqDrawingOrderToFront = 1
bqDrawingOrderUndefined =0
This example shows how to position the trend line to the front of the other chart elements:
ActiveDocument.Sections["Chart6"].TrendLines[1].DrawingOrder = 1