In 2000, Mr. Jiang, Yi 江毅 found that the overall typing efficiency of Chinese input can be improved by specifying the Tone of the last Zi or word when typing Chinese. This helps to reduce around 3/4 unwanted candidates. He invented a method (called 汉王简声调助拼 in Chinese) which assign the four tones to the leftest column of keys on a keyboard. Top-Left-most key (~key in US Keyboard layout) corresponds to tone 1. The second key on the leftmost column (Tab key in most keyboard layout) corresponds to tone 2. The fourth key on the leftmost column (Shift key in most keyboard layout) corresponds to tone 4.