What I meant is that a4' cannot be reached from a3.
My description was not complete, though, as I did not mention what would happen when a move starts from or ends on a4/a4'. I understand now that when you end there you have to choose which of the two to occupy. Which is only relevant for when you move into the upper board half; a move into the lower board half would always look as if you started from a4.
What I meant is that a4' cannot be reached from a3.
My description was not complete, though, as I did not mention what would happen when a move starts from or ends on a4/a4'. I understand now that when you end there you have to choose which of the two to occupy. Which is only relevant for when you move into the upper board half; a move into the lower board half would always look as if you started from a4.