By Lan Tian
From the club magazine, No. 6, p. 7 of Jianquan Taijiquan Association Shanghai from 15.08.1982
At this years’ second Annual Meeting of the Society  Ma Yueliang explained in his introductory lecture the five basic foot positions: pingxingbu, xubu, dingzibu, gongbu and mabu. These five are characteristic positions of the feet in Wu style Taijiquan When learning and practicing Taijiquan one must take care of body postures and understand the changes between yin and yang, full and empty..
At the beginning when learning Taijiquan, often most attention lies on the movements of the arms and hands, and the foot positions can be a little neglected. If pingxingbu is not really parallel (pingxing), the distance between the feet varies, or both legs open like a "v", then this type of foot position leads, for example, in "Step Back and Repulse Monkey (daonianhou)” to non parallel steps and thus the body will be not straight and be without balance.
If gongbu has no bow (gong) and xubu no emptiness (xu), then in the body postures of “Brush Knee (louxiaobu)" or "Scout on Horse Back (gaotanma)" full and empty are not separated and double weighting (shuangzhong) occurs. Or when one turns 45, 90 or 180 degrees, the pivotal point is not on both toes, you also turn on the heel until you reach pingxingbu or xubu. Otherwise the center of gravity is not stable, light and agile. Or, if for example, in "Single Whip (danbian)" or "Fan through the Back (shantongbei)" the foot position is not mabu, then the legs will not be strengthened and the qi not be lowered effectively.
In summary, one can say that if you do not have accurate position of the feet, it is impossible to develop the principals of "Relax Shoulders and Let the Elbows Hang", "Straight Back", "Let the qi sink into the dantian", "The Coccyx is Upright and the Spirit (shen) Reaches to the Apex" and "The Whole Body is Light and Mobile (ling), Erect Head and Empty Neck". Thus you will not develop good Taijiquan.