Least Squares Notation

I’m having a hard time interpreting what i, ‘x’, and ‘y’ are on this page: https://www.gams.com/latest/docs/S_LS.html.

How do I format this accordingly?
objectiveFunction… tc =e= sum((k,tau), sqr(a(k,tau) - e(k,tau)) );

Hi
The ‘x’ and ‘y’ are just the column headings for a table with the x and y values.

set o Observations /o1*o12/;

table data(o,*) Table with data
      	x     	y
ob1 	1     	2
ob2 	2     	3.9
...

Your example looks fine.
Cheers
Renger