Cm is the old name of cm, with the same length. China's ancient weights and measures are now called the market system. When western weights and measures were introduced, China's Chinese characters were added according to China's custom. Such as meter, centimeters and millimeter. These old names were later changed to meters, centimeters and millimeters.
The traditional units of length in China are Li, Zhang, Chi, Inch, Xun, Jie, Fu, Zhi, Yi, Bu, Chang, Ya, Yan, Ji, Rail, Luo, Millimeter, Li and Min.
A few European and American countries, mainly Britain and the United States, use English units, so they use different units of length, mainly miles, yards, feet and inches.