doc -e W {}

to cycle through all the worksheets. My problem is that I can't use

layer -i dataset

because then the dataset is plotted against the worksheet's X column. How can I
explicitly state which column should be plotted against which?

Thanks for any help
(BTW, I would appreciate a quick reply... I got to have this done very soon!)

There is a way to do this using the set -x command. You can plot your Y data
against it's default X column and then change the X dataset after it is plotted
in the layer. Please see the following simple script:

Assumptions:
1. The graph window is active when the script is executed.
2. You are plotting the second column in each worksheet.
3. Data1_a is the X dataset that we will associate with each Y dataset.

%W=%H; //Store the Graph window name
doc -e W {
%B=%(%H,2); //Set %B to the second column in each wks
win -o %W {
layer -i %B; //Include the dataset in the layer
set data1_a -x %B; //Associate data1_a as the X dataset for %B
};
};
rescale;

I tried your suggested script and it basically is what I was looking for...
I couldn't find the rescale command in the documentation though. Did I miss
it or is it not documented?

"Rescale" is a built-in Origin macro. It is very simple; it is defined to
rescale the axes by executing the layer -a command.
You can find out how macros are defined by typing into the Script Window:
define macroname;

For example, if you type:

define rescale;

You will see: