This latest pedantic rant will be on the use and nomenclature of the ever popular and often vaguely understood term RYU.
The literal translation of "RYU" is drive(or flux // on march // river // slobbery stain // stream // streaming motion // tide // trend)
It is akin to the perpetuation of various genres of music or fashion.
The kanji that is popularly used these days, as with other modern kanji, is a cursive version of what was at one time a more obvious pictograph. This is to say that it's older version was more easier seen and understood by it's aesthetic property. However, if one looks at the kanji with the pictographic meaning in mind, one can see the intended artistic message.
In this case, we see a two part picture.
The left side is a flowing stream.
The right side is a child being born.
If we understand and recognize kanji, we already know that the kanji for person is shi, ie: BuShi Warrior or Martial guy / girl. KyoShi = Wizard or wize guy.
Another usage is as a symbol of generation, as used in NiSei or SanSei.
In an old article that Dave Lowery wrote for Black Belt Magazine, Lowery writes that the right side of the kanji looks like a dripping newborn.
Personally, I feel that the pictograph is of a newborn actually coming out of it's mothers loins.
It would be good to note that the term Ryu is not an Okinawan idea at all.
It was first used in Okinawa by KaraTeka, when they began to export their arts to mainland Japan, in order to blend in with the Japanese vogue of order and organization.
A RYU con notates the old Japanese pyramid hierarchy structure of an art form.
An art that is a recognized, "by the Ryu's Powers That Be," offshoot or subsidiary of the parent art or Ryu is called a RyuHa.
A RyuHa will usually have some unique aspects, such as it's own prearranged sparring routines, additional techniques, and often new kata.
This is not to say, that the parent Ryu's properties should or would be discarded and or disregarded.
Ryu Ha often use the term Kan or House, such as GoJu Ryu's MeiBuKan, ShoreiKan, JunDoKan etc.