Van's response, taken from another thread . . .
. . . is exactly right -- this is WCK's "operating range" (what we call "the phone booth"): you NEED to be at that range or closer for the WCK tools to operate/work.
But that's only part of WCK's operating system. From my training with Robert, I came to see that WCK has four elements/aspects to its "operating system". These are things that need to be in place in order to make your WCK work.
First is WCK body structure, What that means is that you can use your body like a spring, to "receive" pressure without moving/collapsing, etc. The kuit "Lai Lou Hui Soong, Lut Sao Jik Chung" (As he comes, receive; if he leaves, escort. Charge in upon loss of contact with your opponent's hand) describes this body structure and how it responds to pressure. You also need to be able to strike with this body structure (which doesn't involve rotation).
Second is facing (the square-on facing of our opponent).
Third is range (that we are within arm's reach of our opponent's body).
Fourth is WCK bridge structure (that our arms are between our body and the opponent's body and that are elbows are down and in - inside our body line). Some call this "the fixed elbow principle".
When you deviate from these four elements, your ability to use your WCK tools or movement or actions will be greatly compromised.
And, Robert showed me that if you look at the first several points of all three empty hand forms, you see that these elements are emphasized -- the first point in all forms is the opening of the horse or bai jong, assuming body structure; the second point in all the forms is the sup jee sao, the crossed arms which points to the square-on facing (and with that, the ability to use both equally hands at the same time -- which you will need to do); the next point is the opening punches, the jik chung choi which points to the range (you must be within an arm's length of your opponent); and, in all of these, your arms are between you and your opponent and your elbows are down and in (which connects your bridges to your body structure - the elbow-down power). Everything that follows, with only few exceptions, require these elements to be in place.
So, in terms of "application", if you don't have body structure, it doesn't matter what else you do, your WCK won't work. The form -- a living textbook -- "tells" you that if you want your WCK to work then assuming structure (bai jong) is your first priority. And everything else that follows depends on that structure being in place. Next is the facing. Once you have body structure in place, you need to face your opponent properly (square on). If your facing is off, you won't be able to use the WCK tools to their fullest. And everything else that follows depends on that body structure and facing being in place. Next is range, being within an arm's length of your opponent. If you are at a greater range you won't be able to use the tools (your body leverage decreases, etc.). And everything else that follows depends on that body structure, facing, and range being in place. Finally, you need to have your arms between you and your opponent with your elbows down and in.
For me, this is WCK on its most basic level: are these four aspects in place and always operating - in your drills and in your application?