The morph DIAL may move in two directions, but that does NOT mean that the morph necessarily "reverses" properly when taken to the negative. This is why I have separate morphs for "quillion 1 up" vs "quillion 1 down" on my morphable dagger. Merely dialing "quillion 1 up" negative does NOT give a proper down curve to the quillion. Instead, it makes a mess. Thus, I want to combine two such targets into one dial, one for the positive and one for the negative, since they are at least conceptually "opposite" to each other even if they are not mathematically so. This is also the reason that I have separate "long blade" and "short blade" morphs. Both of them get into bad weirdness if dialed into the negative.