The expression & ltp> originated from the British Commodity Exchange and was first used in 1877. At that time, the British Commodity Exchange divided each month into four weeks, which were represented by 1, 2, 3 and 4 respectively. For example, the first week of January is represented by 1, the second week by 2, and so on. Later, this notation was changed to letters to indicate different months, and now it has become an international standard. & lt/p & gt；