Wushu Among Chinese Moslems has one of the worst titles of any Chinese published book. The cover picture is of a fez-wearing Moslem with a Kwan Do. To most westerners, this image is a strange clash of imagery. A close friend of mine who knows that I practice Kung Fu, but knows little of Chinese culture, actually gave me this book as a joke, since he thought it was completely absurd. The Hui are famous for their martial skill.
Later sequences suffer from more unstable transmissions.
Over generations, various masters make alterations and improvements, possibly filling the gaps of anything that might be unclear, until the set evolves into an entirely new sequence. At this point, it would be difficult to determine which set is more accurate to the original. This information is not particularly relevant anyway. Validity of any set lies within meaningful execution. As long as all four variations retain their applicative intent, they all retain their validity.