What is a Ryu:   As a natural course of events; after many years of teaching the average martial artist soon finds himself departing from the methods of instruction,  which he was taught and teaches what is in reality, his own ryu.  His teaching is drawn from his experience and techniques learned over many years.   A ryu by defination is taught by a martial arts family and passed down from one generation to another.  Aside from that, there must be some defining and or distinguishing characterstics.  You can't create a ryu by simply combining a kata here and a technique there or by just changing the name of an old ryu.   The first place to began is with enough knowledge and experience to be able to develop an intelligent improvement.  A ryu must stand firmly on a foundation of scientific principles of physics, anatomy and philosphy.   Determine the underlying philosophy of your proposed ryu, try to outline it in as much general and specific details as possible.  This is the begining of defining the basic guidelines which will be needed to set the parameters of your ryu.   It will be necessary to itemize the scientific principles which will be the basis of your ryu,  which laws of physics and human atamony will you stress?   As you work through you ryu, you must take a definite view of technique and how it is to be taught and performed based on it's underlying principles and philosophy.   You must then determine which techniques are to be taught at which rank and what set curriclum of teaching needs to be developed.   The philosophy of a ryu gives direction to the art, Bushi Ryu Ju-Jutsu is an excellent example of this in that it has a philosophy of preventing future violence.  Thus all techniques are approached with the idea of Contact, Capture, Control.