The shape and length of the apex can be different. It can even sometimes be different within the same writing. While pretty much all apices are made up of a line sloping up to the right, the line can be more or less curved, and is different in length from less than half the height of a letter to more than the height of a letter. Sometimes, it is put at the top with a hook, pointing out to the left. Rather than being centered over the vowel it changes, the apex is often drawn to the right.