I often need to visualize several curves of x-y data series in a single chart. I
have spend much time in vain looking for a way to assign data series for each
trace individually. That includes reading the on-line help, so I assume this
feature is not available. Example:

Curve 1: X-data: A1..A10,  Y-data: B1..B10  (e.g. primary sample data)
Curve 2: X-data: A1..A10,  Y-data: H1..H10  (e.g. Curve 1 after some manipulation)
Curve 3: X-data: A18..A36, Y-data: B18..B36 (e.g. reference from previous sample)

These three curves I need to plot in a single chart using the same Y-axis. Note
that:

Curve 1 - is trivial.
Curve 2 - has "space" in data range (columns B-G are skipped)
Curve 2 - has individual X-data range of different length and location

Other spreadsheets I have used have had this feature (Excel, 123, XSlite, SC).
If the feature is available, please give me a hint on how to address it.

And ... thank you very much for the efforts you put into OpenOffice.org.