It's also quite common in handwriting; ij in cursive looks exactly like ÿ, and even when the letters aren't all joined, that is a common ligature. When I studied

It's also quite common in handwriting; ij in cursive looks exactly like ÿ, and even when the letters aren't all joined, that is a common ligature. When I studied Flemish as part of the integration course, all of the teachers wrote ÿ, and so I presumed that it was just the done thing.