The Central Line Area is divided up into Six Gates with the Central Line in the middle.  These gates are also divided into three levels that are named upper, middle, and lower.  The names of these are the following with the Central Line splitting them in half is Upper Left, Upper Right, Middle Left, Middle Right, Lower Left and Lower Right.  The Wing Chun practitioner uses zone defense concept instead of technique-to-technique base system.  For the Wing Chun practitioner it is easier to learn to protect an area or close a gate than to remember many numerous counters for a particular attack.