Hi Gerold,

Thank you, we have received your sample, and I see that it seems that 
your graph was created by some sort of script as with a loose dataset, 
but I'm not exactly sure. 
Anyway, your graph is a ternary graph which contains two scatters as usual, 
and also a line plot with "Fill Area Under Curve" property. This is not terribly 
strange, and I don't think scripting is a must. You can use a template 
if you need to create repeatedly. 

Here is a step-by-step procedure: 

1) Highlight C(Z):HP column in Book1 for filling area, and 
   make a Ternary graph as usual.
   (Please notice that I have put Long Names and Unit in header rows 
   so that the legend and axis titles would be shown nicer by default.)

2) "Format: Plot Properties" menu to show Plot Details dialog, 
   and select "Line" for the Plot Type at the bottom left of the dialog.
   Press "Apply" button, and now, you see the border line for filling.
   (Instead you can simply press the "Line" plot button in the 2D Graphs toolbar.)

3) In the dialog, turn ON the "Fill Area Under Curve" check box, 
   select the Pattern tab, and select the Fill color. (Cyan in the sample)
   Click OK to close the dialog.

4) Double-click the layer icon"[1]" at top left corner of the graph, and 
   double-click it to show the "Layer Contents" dialog.
   Select [Negative]!HP(Z) in the left panel, and press "==>" button to 
   move it to the right panel (i.e., into the plot). Then, select 
   the moved item at right press the dropdown button to select "Scatter" 
   (changed from "Line").
   Do the same for [Positive]!HP(Z). Press "Close" button to finish.

5) Choose "Graph: New Legend" menu, and customize the symbol color, size, 
   etc. as you wish. 



Once you created a graph, you can save it as a template ("File: Save Template As" menu.) 
To make another graph using this template, you can use the template library 
to open it, and you can add the Z datasets in the same order to the above, 
i.e. the border dataset, Negative HP, then Positive HP. If you like, 
a simple a-few-line script can open the template and put the data to make a new graph.

--Hideo Fujii
Originlab