Extension Pattern: By definition an extension occurs in an impulsive wave, where waves 1, 3 or 5 can be
extended, being much longer than the other waves. It is quite common that one of these
waves will extend, which is normally the third wave. The two other waves then tend to
equal each other.
In our pattern definitions we call it an Extension1 if the first wave extends, an Extension3 if
the 3rd wave extends and an Extension5 if the 5th wave extends.