In certain cases, I have added sketch lines to my drawing and placed them in the layer titled "CENTERLINE".  Its line style is phantom and the color is red.  When I export to DWG, all the layers and colors export as expected, except for the sketch lines; they get placed into the same layer as the model.  All the centerlines stay on the CENTERLINE layer, but the sketch lines are moved out of it.  I don't have any custom mapping set up and I've tried both "SolidWorks Custom Styles" and "AutoCAD Standard Styles" for exporting DXF/DWG "Line styles".  Is there any setting that is causing this to happen that I'm unware of?