If there are two pieces of the same type that can move to the same square , one more letter or number is added to show the file or rank from which the piece moved , e.g. Ngf3 means `` knight from the g-file moves to the square f3 '' . If there are two pieces of the same type that can move to the same square , one more letter or number is added to indicate the file or rank from which the piece moved , e.g. Ngf3 means `` knight from the g-file moves to the square f3 '' .