Kenpo definitly has the "tools" to help us talk about our System, and convey it to others, but in this case the "zones" have been around other Arts also. Whether they were borrowed from Kenpo (a rather egocentric statement on my part) or whether Mr. Parker saw a piece of them elsewhere and then flushed them out by analysis, and restructuring into a more sophisticated tool, I don't know.
Wing Chung, in all it's myriad of spellings, has always had the centerline and 4 gates. JKD uses this still in their training. I have not heard anything close to outer rim. Everyone knows the JKD / Kenpo relationship was close due to Mr. Parker and Bruce Lee's relationship, along with Dan Inosanto and Mr. Parker. What starts where, I will never know.
Where I get hung up is getting across to my beginners the idea of keeping your hands in front of you, and protecting the space in front of you, not keeping the guard so close to thier bodies. It does not seem to matter how many times I can touch them, they tend to revert back to that "close guard" when under pressure. It leaves them with no time to react after perceiving the attack. I have not called it a "shield", but thanks for the idea and I will try it.
-Michael
UKS-Texas
