Question about Stack and Roll

[Antlab]

Thanks a lot.
If I understand correctly, the answer to my doubt is explained by the effects of the flag created by pressing Enter and removed by pressing Roll Down, as Wojtek illustrated. I did not know about the flag, this makes sense now.
Actually, Sylvain, also your example is helpful. I think you obtain a slightly different result because I did not press Enter after inserting the final digit, 4.
I will make some further tests, but I am glad I asked here, because in the manual the question of the flag was not clearly explained.