Thank you for your explaining a lot.
And, I had thought that to copy and paste equations to a new worksheet from the previous one often might bring wrong spelling of equations.
But, I thought later that the following way might help avoiding that.
In original worksheet,
are written, and then suppose that you execute that worksheet.
Then, in the current directory, which you can ascertain with
a file with the name myfile with the next contents is made.
r0 := x^3;
r1 := 3*x^2;
r2 := 6*x;
r3 := proc (y) y^3 end proc;
And, after opening a new worksheet, you write the followings. The lines with ">" is those you enter into maple.
So, on moving to a new worksheet, what is necessary is to save some equations which are necessary in the new worksheet into a file: in my case "myfile," then to read it in a new worksheet.
Through using and managing a file,"myfile" minutely, in which the names of variables are written, I thought, I might be able to avoid the situation that I pay a lot of efforts to find variables, and it might help in making what I write in a file compact and easy to see.
Later Addition(Oct 30, 2016)
I decided to make a mpl file where assigned variabes are listed, with save, and in a new worksheet, to read it, so that I could make that workseet as a note of names of equations, which make it easy to enter codes. And, I wrote a workseet where I wrote a package containing
codes. And, now, I am using that package as you taught me in the above reply. And, as for labels of equations, I think I will have maple show it as when I see a worksheet, I think it will make it easy to see which part I am seeing.