DPlot

I work with a lot of data that is overlayed with reference data and my typical solution is to order the curves such that the reference data is behind the data of interest. However, it would be nice to be able to change the reference plot to be transparent -- just a shadow in the background -- so that it doesn't detract from the data of interest. Is there any way to make a line transparent so it blends into the background? I've tried using the symbol opacity feature but I'd like not to have to use symbols -- I'd like the lines to be transparent.
Thanks!

No, there isn't any direct way to do that. About all you can do presently is to create 2 separate documents, then overlay one with the other with an OverlayDocument macro command, playing around with the transparency values. See http://www.dplot.com/forums/viewtopic.php?t=828 for more information; OverlayDocument is currently available only as a macro.